There is a group on Chess.com you can join to discuss online cheating, it is typically forbidden on the main forums. That said all online platforms with cheat detection systems, Chess.com included, have procedures and benchmarks to hit before closing accounts. If you believe anyone may be cheating, report them and let Chess.com handle it from there. In my experience accounts slow to be closed for cheating are often a result of insufficient evidence/poor reporting by the offended player, or the suspicious play is not sufficient to meet the benchmarks needed to close and they need more time (evidence of foul play) before reaching their benchmarks to close the accounts. Keep in mind that online play should be viewed as for fun and self-improvement, whether you're cheated against or not they can't stop you from learning to play chess better, and whatever rating hit you may temporarily take for the unfair loss is not going to slow you down long time. We'd rather have less false positives from websites being thorough in their cheat detection than banning anything that looks remotely suspicious and losing many players unfairly. Think about it if you got reported and banned from a good game you played when you did nothing wrong- how'd you feel? 
-Jordan
It seems to me that this website is very slow at banning cheaters. It is not that rare (at least at my level) to see occasional cheaters with some insane games (in which they are not even trying to hide that they used an engine, I guess smarter cheaters are more difficult to catch...) and yet, they have accounts of 2 year old or more...
I (as probably no one) don't really know the solution to this problem, but I feel that a reputation system for players would benefit the matching system (maybe there is already one behind the scenes?)