Nobody likes a troll. Even less people like being matched with someone that they know is only there to troll, grief and/or just make the game miserable for others.
I spent twenty minutes jumping in and out of matchmaking on Chaos Rumble 'cos I kept getting matched in with the same guy. Never picked a character, remained AFK the whole match, and played some ■■■■■■■■ faux-RNB over his voice chat (up til I muted them anyway.) I stopped playing because they were always in the queue, and always matched with me.
I reported them (obviously), blocked them on Steam, but they still got matched in the same group with me over and over. Halp.