Lagging out of a game and getting a 20 minute ban afterwards is a huge deterring effect to continue playing. Make the matchmaking bans for excessively leaving the game, not every single time you leave. Keep the bans in place for competitive play, but if I want to leave a BTB game where my team is getting spawn trapped and just absolutely destroyed, I should be able to do so without a ban.
Hey OP, please use the ban thread pinned at the top of the main MCC forums for any queries on matchmaking bans