QKO is level 3, so level restrictions wouldn't help there. Also by preventing the low level players joining "normal" games, they'd take longer to discover "how it all works", unless they are lucky enough to get more structured training like you suggest. That'd include stuff like how it's a team game, and how ignoring everyone and just doing your own stuff isn't going to get you anywhere...
And for QKO... Yes, surrendering is less easy, but ragequitting is lame, so...
Quite likely the troublesome players will quit after the match, especially if you tell them why you surrendered. You can report them if they are persist in being nuisances. You can also create a new lobby, or just jump to another existing one. Presumably this is what you'd do if you had just quit, so surrendering doesn't really make a difference here...