Despite the attempts to stop players from switching teams during the faction locked campaign, there are still legitimate ways to do so.
For instance, you could pay for and play multiple accounts (not simultaneously — that's called Multiboxing and that
is against TOS) and bind your accounts to different alliances in Gray Host.
Here's a snippet from Bethesda Support just for clarification on that:

Not only that, but even if whole households could be locked to a single alliance per month, that wouldn't prevent people from griefing/trolling just for the fun of it. You could be on EP and purposely drop scrolls in the river so AD and DC can't retrieve them. You could grab Volendrung and just give it to the enemy factions because your friends on the other factions want it. Even if you are truly locked to one alliance, bad actors will continue doing what they're doing — whether their team benefits from their actions or not.
So why have a faction lock at all? I personally think that there is some merit to making it difficult to swap your team; while a faction lock doesn't totally prevent bad actors, it can at least dissuade some of them. Fewer people would grief if they couldn't swap teams to benefit from it.
My main issue is with how long the faction lock actually is. For an entire month, you dedicate your account to one faction on Gray Host. If you're part of multiple PvP groups, you're out of luck if they decide to move to Gray Host when you had previously played with a group of another faction. One month is a much longer commitment than four hours.
The purpose of a faction lock should be to dissuade faction swapping in the short term, not the long term. While we
could operate multiple ESO accounts just to play with our friends on different factions, I believe that the faction lock is trying too hard to prevent something that can ultimately be bypassed through legitimate methods.
Alternatively, methods to diminish the effects of such griefing should be looked into. Maybe scrolls when dropped into rivers should be warped to the shoreline?
PC/NA — Lone Werewolf, the EP Templar Werewolf
Werewolf Should be Allowed to Sneak
Please give us Werewolf
Skill Styles (for customizing our fur color),
Grimoires/Scribing skills (to fill in the holes in our builds), and
Companions (to transform with).