While it probably happens to some extent in all campaigns, I've not seen it in the big ones (Wabba and now Thornblade)...but on many of the other campaigns, guilds go to them for the specific purpose to farm Emperor. They are very vocal about it in chat. Don't attack this keep, it's AD's turn. Don't attack that one, it's DC's turn. They swap back and forth and collude with other Alliances to open gates for scroll runs. I don't think that is what the developers had in mind when they designed this system.
If you take this out to it's ultimate end, you will have those guilds with huge numbers of former EMPs using their EMP line to farm high end content and create a great divide between the haves and the have not. I don't like playing against folks that are stronger than I am because they've exploited and gotten rewarded for it. But, under the current game design that is exactly how it is happening.
My question, why do former EMP's have a skill line at all? If they keep it (and I don't think they should) then why do they get to use it outside the specific Cyrodiil Campaign they earned it in? Can someone from ZOS answer that question please?