I mean, when I joined my Diamond-rated friends for some comp, here's a sampling of some of the assholes I had to deal with.
For example:
Haha. Sheeeeeit.
I'm gold/plat on PS4. Nobody speaks; I only converse with my real life teammates. This is good, as many gamers are either wankers or twelve. Playing with either makes me feel bad.
The worst matches are the ones where you can tell by everyone's characters that nobody cares about team composition. They just want to play their mains. People trickling in. I have to decide between either being a healer or a tank. These matches are 33% of the time, in my experience.
The other 33% of the time there is some awareness of team composition. People spam healers/tanks when selecting to force a pick on someone. Many solo-healers. Sometimes a good composition, but still trickling and bad decision making. I don't usually mind that much, because you're probably playing against a team that's doing the same thing.
The best 33% are matches where there is a lot of communication, if only it's "group up" and ultimate calling. They're overtime matches, they take long, they're intense, and they actually make me say: this was a good match, even though we've lost. I expect the folks in platinum/gold playing these matches are the more hardcore players, the ones who check streamers and tips and have meta-awareness.
If you're a console gamer and have really good aim and play McRee or Soldier for instance, you will quickly rise, because that shit just wrecks us more casual players.
And no communication with randoms = good.