You really should allow people to move team at least one time. A lots of people didn't understood correctly and are now f*** up playing without their friend in all the guild i'm in. That really frustrating and not fun at all.
That happened to my brother, he comed back to the game like 1 week ago, We used to do wvw together past prime, he logged on without me, wasn't there for speakiing to him about change, he just logged in etenerl battlfield and got randomly put in a team. nothing advvertised him of the change, just a click, loading screen and he was in wvw and now we can't play together the wool week great.