Telling people to switch because you don’t like their playing ability is just going to insure that they don’t get better.
When I first started out as Mercy, I was pretty bad (as most of us were when we started) I didn’t have much game sense and was usually a healing only.
But as a I played more games and got in more practice, I got better and better.
If you want to have those awesome players on your team, you’re first going to need the bad ones. They’re not going to get better with a clap of their hands.
Also - there are 5 other people on the team, including yourself.
I’ve played where there were some people who were trolling/throwing (and not actually learning to play the character), but instead of whining and complaining about it, we played around them and went to win.