Actually there are other factors involved, like being able to choose the average gear level of players you bring, as well as choosing what class and even what talents people need to have, because there’s the option to decline players.
There’s no such option in a random matchmaking system.
That’s a very shortsighted statement, it’s actually due to the social design. You’re more likely to speak to players you’re familiar with, i.e. “communicate”, than you are with complete strangers.