Right... sure they're not...
In fact, this was quite the opposite, where you had people being "oh great, I got the winning team again" and LITERALLY doing /sit for part of the match because we had the win on lock down with no hope of counterplay by *either* of the other teams, even when they pinched us (hence my 1 death).
I would not be shocked to find out most of the other two teams also started AFKing at some point, and they'd be justified, because premades *encourage* lethargic gameplay, always have and always will, winning or losing.