It just creates such imbalance. Not to mention uneven teams when 5 players all at once join a team. Just played a match 12 v 18, of course there was a premade on the other side. By the time the game finally made up the -6 player difference, we were already being spawn camped.
You can still play with your friends. I played css on 40 player servers with my friends and actually made new friends. Cause it just filled teams one player at a time.