Yes, but often people have problems to find time for playing AT together, and then it is more often easier to play teamgames with random teammates, and hope that they are good players.
Often in teamgames with random players, it is 3 vs an arranged team of four good players. The matchmaking either gives one who drops early, or one who is a beginner who does not know how to play the game, and then the arranged team attacks the weakest link in the chain (often unintentionally), and the team with random players collapses and loses the game. Maybe the beginner player will stop playing 4vs4 with random players because of this, and we have a smaller player base.
I totally agree with you, but if you have good RT and win over AT. It is amazing experience.
And smaller player base. If Relic separate AT teams in 2v2 and above, thus destroy 3/4 player base.