A lot of the responses from players already covered things (thank you!), but I'll also add some notes before locking the thread.
Developers (and other staff, like Game Masters, Community Managers, and Artists) are very often in guilds. The longer you play the game, the more likely you'll find a good home of people to spend your time with here, and personally, I think that's great.
The Devs do not all play one side, or even guild. (Though if you believe the forums, they all play whichever side you are not currently playing.
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As an example, the team member leading on RvR mains Destro, and runs a guild there. I've been in dungeon jail and haven't played much the last few months, but I lead a guild that primarily plays Order. Our Community Manager runs one of the largest guilds for Destruction, while another Scenario team staffer is an officer in an Order guild. The reality is that you'll find a great mix of staff across each faction, and many who play both.
I realize 99% of you reading this already knew this or could have guessed it, but hope this makes things a bit clearer for the rest!