Only thing that calms toxic throwers is a ban. The commendations aren't for them. They're for the people trying to improve the game and their experience of it. The people turning every match into a 4v6 have a lot of problems that have nothing to do with videogames. They suck at people.
I know because I was one of those people. I can still freak out sometimes, but I stay on push to talk and try to keep with questions rather than commands... although "where's the team?" is a grey area I'm working on.
But when I keep my shit together and am encouraging under fire it feels really nice to see a "You're a swell teammate" little award thing. Just a little extra incentive to keep it civil.