If I can provide proof that an artist on here is a repeat scammer, would this site do anything? I know they already don't care about worse stuff like racism, homophobia, antisemitism, etc on here, but maybe they'd do something with this at the very least.

What a wacky thread.
It seems to me that you are more interested in complaining about this site than actually someone being a scammer. But that's just me.

We do care about people being racist, homophobic, antisemitic, etc. on this site. Same thing with scams.
We aren't internet police though, so we won't be deleting artwork because the artist had been a shitty person elsewhere.