Everyone is approaching this from a "noob" perspective when the solution is easy. Group new players into the same matches for a couple dozen matches (varies on the game) and all the other players are in the same lobbies. It wouldn't help with smurfs, sure, but I'd say that smurfs would be less of an issue as there are more casual players than there are sweats in the lobbies. This would need some refining but it could easily work.

This would benefit everyone, because if the newbies are still really bad then they can play ranked and go against people of their own caliber, the majority of players are playing against each other at their own skill level instead of doing well in one match and getting placed in a high skill lobby, and the sweats can relax and mess around without having to compete against other sweats constantly.