There should be an immediate 15 minute ban for the first offense; 30 for the next; 60 for next; etc. You SHOULDN’T get penalized for leaving after others have quit, though.
It’s ridiculous how often people quit within the first minute of a match.
There’s also a bunch of people who quit while you’re winning, because they’re individually getting destroyed.
Most games add others mid-game. That can be annoying as well… But it’s still better than this.