It seems as if the ‘game masters’ have decided that if you are not V5 you should not venture into Cyrodill, and, if you are not V10 you should not consider trying to solo any of the quests or dungeons on the frontier.
I can understand one of the points to the change in Mob level where a small number of V10 (or now V12s) could basically steamroll through a keep and its resource points with very little effort. I believe their change has completely eliminated EOS's, for lack of a better word, promise:

“Player vs. Player (PvP) in The Elder Scrolls Online is fun, rewarding, and accessible for PvP veterans or new players with no PvP experience.

The Elder Scrolls Online features a battle leveling system that temporarily increases a player’s combat effectiveness to compete against higher level players, ensuring that everyone enjoys the experience, from players who have never experienced PvP combat, to seasoned veterans demanding a deep, rewarding PvP experience. Players may join the PvP action as soon as they reach level 10, and jump right into the action without fear.”

In all honesty there were better ways of handling this like:

• letting players purchase upgrades to keeps and resource points that increase the guard strength.
• Having guilds or even groups be able to greatly increase the defensive strength of keeps and resources quickly.
• Having a buff that is the exact opposite of battle-leveling where players higher than V1/50 get buffed back DOWN to the V1/50. That is to say have battle-leveling in both directions.
• Preventing 1 player from easily operating 3, 4 or 5 pieces of siege equipment.
• Fixing siege damage elimination exploits quickly.

Now as far as splitting the PvP game into level sections – almost every MMO with PvP has tried that and failed – badly. One of the earliest was DAOC where they had battle grounds for 20-24, 25-30 etc. What you found was that the 20-24 was full of people who were making twinked 24 toons, the rest of the leveled battlegrounds were devoid of life. STOR had similar issues. It’s a bad idea to split your players like that in a realm vs. realm battle where the enjoyment is directly proportional to how many players participate.
Finally, having mage and archer guards 1-shot players who aren’t V10 is no way to run a realm-war.

As it stands now, STAY OUT OF Cyrodill unless you are V5 or higher and in decent gear because it isn’t fun and the repair costs could empty your bank account.