Report them as stalling/Quitting Games
My opponent gets black, and 80% of the time they quit

Are we talking abandoning the game before their first move? I've seen this as well - but it's a small percentage.
One of the things that I've come to appreciate is that chess.com attracts a huge variety of ages and cultures and chess etiquette is not something that a young kid has necessarily yet learned. I cut those guys some slack. What I (still) can't stand is those people who disconnect rather than resign - as they leave you hanging while they can go off and do whatever they want.

I think it’s time chess.com started punishing these time wasters.
If they do it to often they get a warning and if they continue I think they get a brief time out.
I think it’s time chess.com started punishing these time wasters.