I was wondering, what's the reasoning behind not allowing 5 players CC queue?

Is this about win trade? Pretty sure things could be done about that like preventing the same two teams from fighting each other more than once every 10 fight or something.

At the fan fest we also saw team fighting so how come they managed to make teams? Just using the pf customs matches?

It is a bit disheartening because it's like the only content you can't play with friends.