Seriously, come down off your high horse. Not everyone cares if they win or not when it's not ranked. I myself play the heroes I enjoy. Mostly Junkrat and Genji. Sometimes I'll que 4-7 games straight as one hero because I wanna try and get better with them or whatever. Why sould I change my way of play just because you feel it is the wrong way to play at the time? There is no real reward to winning expect more XP a bit of an MMR increase. So what if we lose? It's Quick Match, it doesn't drop my rank or anything. If it was ranked and ranking or rewards were acutally on the line, then yes, you'd have more of an arguement. But people are still allowed to play how they want.
It's no different than someone solo queing QM in HotS as Tyrande or Kara and going dps spec as the only support. I wanna play Owl/starfall build and have fun and not be forced into healing for the 9th game in a row or something.
TLDR;
Not everyone cares about winning, some wanna have fun. If you disagree with this, find friends that agree with you.