One of my biggest pet peeves that some players do
I don't know if this goes away above platinum, but plat and below people wander around the jungle without vision, fight, a few teammates join in, so they're left fighting a 3v5. All the while, their teammates are pushing out side waves and/or getting objectives or at least vision on them. What do those people who are fighting over wolves do? Flame their team for actually trying to play the game out.
This is probably the thing I get flamed for most and the thing I see people flame for most. Your nasus is split pushing top and your swain is split pushing bottom? Why are you hard engaging 3v5 OVER RAPTORS? I could at least understand if it was a major objective, in which case obviously your team should be grouping over it. But it isn't even that, it's just people wandering around, getting caught out, then blaming their team for their own mistakes. Ugh, it's so frustrating dealing with people like this.