It's RMT. You only have to spend about 60 seconds to contact them and see for yourself. People saying otherwise are arguing just to increase post count or are trying to mislead for some odd reason.

As for the OP: It is against the ToS, but the GMs won't do anything unless the ads say 'we sell for monies' and the STF doesn't use discord info, so until SE changes their stance, it's allowed.