I said it once, I said it twice, I will say it again. The problem doesn't lay in the sphere of "becoming blue". This is something the one can get used to.
The problem is during the situations, in which bunch of players ruin someone else's roleplay by butting in and going for easy blues - knowing the other player group will be no match for them.
This is preying on the weak, not a "healthy rivality" as some people wish for.