Yes, I think they do get banned or blacklisted.
I'm not sure if this is the case. I've heard from posts on this forum that Hermes knows it sells to resellers and they are secretly fine with it, even though outwardly they may say they don't want their bags to get into resellers. It's not possible to know exactly what they think, but they clearly haven't seemed to do enough tp stop resellers. They are literally all over the internet. Brand new bags from "personal shoppers," they even say "fresh from boutique" or something like that. It's really frustrating as a genuine customer would would never sell my Hermes bags ever, that these resellers are taking up stock that could go to us. This is why I will never buy a handbag from a reseller site or pre-loved.