PvP oriented games with roles usually have things that make each role fun and engaging. It seems to me that ESO doesn't know what it wants to do. I think PvP and PvE should have their own sets of mechanics, or maybe even split up into different games if need-be. But this isn't much about PvP anyway...

I'm always tank/support in any co-op game that allows builds like those, it never feels right for me to play a damage dealing build. Always tank.
There was a time when I thought I was pretty good at tanking and had an awesome tank build in ESO (when I was first starting and made it to veteran rank 1, way long before champion points were a thing), until one day I went to PvP and got nuked by some rando. For the player who killed me, that moment for him meant nothing than just killing some casual PvE'er... but for me... it meant playing the next 5 years being insecure that I suck at tanking, because if one single player could nuke me just like that, then my build is definitely not good, so I never played dungeons, let alone trials for 5 years. I missed out on so much content of the game just because A) I didn't feel I was ready to take on it, and more importantly The game really panders to damage dealing builds.
To compliment those two points, when I wanted to try my luck again, I made the terrible choice of attempting vateshran arena as a tank. I thought I was doing well as a tank, and honestly, I was, but as I mentioned, the game panders to damage dealing builds, so I'd get punished for failing a DPS check, and not knowing I wasn't supposed to play as tank, but instead completely change my build to something more hybrid, I still thought my tank build was [snip] because I'd get one-shot no matter how much defense I'd buff up. Which sucks because vateshran is just as equally challenging for tanks as it is for damage/hybrid builds (damage builds have to clear the adds and deal splash damage to the boss, tanks will never clear the adds so they have to focus on the boss while taking a beating from adds, there was absolutely NO REASON to punish tanks for failing at damage when they're already struggling with a different type of challenge).
So yeah, that meant I remained insecure about my tank builds and kept avoiding any sort of content and just limited myself to anything I could finish with my brother.

Then I started taking on normal vanilla dungeons, 5 years too late, I could've piled up on all that gear if that random player in PvP hadn't simply nuked me. When I decided to git gud and looked up guides and builds, I was highly disappointed to realize that the game was meant for you to do a damage build to enjoy 100% of it (all dungeons, trials, pvp, solo arenas), and when they introduced armory, the truth became even clearer: make a support build for a specific purpose, then switch back to damage to enjoy the rest of the game.
So imagine wasting 5 years thinking I wasn't good enough on a build that wasn't meant to be a 'viable' role for the entire game.
The reason why I say the game panders to damage builds is because no matter how awesome my tank build is, I will still get one-shot regardless of what I do because of mechanics and that a 'mediocre' tank would be just as good as long as they know the mechanics and they focus buffing up the damage dealers instead. (I use mediocre in the sense that as long as you know mechanics, there's no real reason to make a min/max tank build... a min/max DPS will always be better than a normal DPS, but a min/max tank can perform just as equally as a mediocre tank)
You already sacrifice so much of your other stats, especially recovery when playing as a tank, and while DPS has a reason to improve their builds to get the most out of their damage, there's no reason to do the same with a tank, so you can either A) Have an awesome tank build that still gets one-shot and nuked in PvP, or B ) Have a mediocre tank that still gets one-shot and nuked in PvP but with like 200 more damage and recovery.

Every update, it makes playing as tanks less and less enticing, the achievement is called "It's a tankless job" because for all the stuff that tanks have to go through, there's still nothing to motivate tanks to keep tanking. There's nothing in this game that makes tanking any fun, but there's an awful lot of pressure to memorize all dungeon and trials mechanics, in PvP you get points for dealing damage, you get points for healing, but there's nothing that requires tanks to do anything, objectives in battlegrounds are ignored because all people want to do is kill players so objectives are just extra steps, and even so, tanking is not required (but if you somehow manage to be a good tank for PvP, you'll get all the youtubers complain that PvP is not fun because they can't kill you in 3 seconds, yes, the real godzilla still complains about it).
Anything that makes tanking fun has to be taken away on every update, I made a thread about power slam, so I'll give the small version here: Power slam could've been a tank skill, tanks are the ones who have to block all the damage, a tank could've taunted, blocked, and then release a massive burst that scales with their health or defense. But no, we couldn't have that, instead now it just gives a 33% buff by blocking ONCE because a DPS/DD doesn't have to block as often, not only that, but the damage done is going to be a CP active perk now, the skill just grants 50% cost reduction for blocking once. So yeah, what could've been fun for tanks is now just (as always) pandering for damage builds.
AoE taunts? Nothing that a tank can do as an expensive skill, instead we have to sacrifice one of our sets (Tormentor allows for AoE taunts). So why do we have to find loopholes to do something that "breaks the game's philosophy"?
PvP taunts? There are only 2 taunt skills, one of them breaks armor, that's about it, you obviously can't force players to attack you, but there IS a set that 'taunts' players (vanguard's challenge) which reduces their damage done by 35% but increases your damage taken by 35% so the player has to kill you first to regain their full damage, so why do we need to sacrifice a whole set just for that? Couldn't we natively taunt players by using 10% instead of 35% (and the armor set would just amplify the effects)?

Giving a tank something to have fun with won't break the game, why sacrifice so much fun aspects of the game for the sake of "balance"?

I sometimes wonder what is it that this game has that has kept me playing ever since it released on consoles... maybe I stuck around because of the potential it has to be an actual fun game, instead, it throws away everything that could've been fun for the sake of balance, and yet it remains unbalanced as heck but without the fun. The crossbow used to pull you to enemies and you could use that to move across cliffs with ease, it was fun, now you can't do that with the crossbow (but you can still do it with sword and shield using shield charge, which is less immersive in my opinion). 2H's spammable used to knock back enemies, now it just stuns them, but you can still knock them back with the templar spear or bow, AND do it from the safety of long range, but you can't knock back NPCs off bridges into the water anymore. It would make sense if the fight was actually hard, but it's overland content, it means you're forced to kill the enemy from start to finish, it no longer rewards you with a quick lootless fight by using the environment to your advantage and what for? If it was a hard fight, it would make sense because it would prevent you from cheesing your way out of a challenge, but it's a generic NPC that will die before they can even reach you anyway. So again, why do we need to sacrifice all that fun, or why even remove the capacity to do any sort of damage as a tank when they're still the types of builds that aren't viable for PvP? It's not like a tank dealing 20k burst dmg every 5 seconds will break PvE dungeons.

Everyone keeps saying that a tank should buff up the team so that they can deal more damage and finish quicker, but how is it any different if the extra damage comes from the tank, and not from the buffs the tank gives the team? At least that way there would be better reasons to make tank builds that are fun AND still play with the same build outside of the dungeon instead of immediately ditching it and switching to DD.
That's why nobody wants to play tanks, and despite armory allowing you to quickly switch builds, there's still fake tanks in PUGs. There's nothing fun about tanking, there's nothing rewarding for min/max'ing a tank build, you'll still get one-shot, mist form was also nerfed to PvP only because whatever creative approach for a PvE challenge was removed.

Ever since overland was nerfed in tamriel one, and other than PvP, what's there to "balance"?

[edited for profanity bypass]