**Ad stuff:** We had an... incident... with another user advertising like this several years ago. It was significantly more hostile than this, but it makes us hesitant about allowing this at all.
There's no precedent for this on other SE sites - Puzzling is the only one with so much focus on questions, and *original* questions at that. So handling things on a case-by-case basis is pretty much our only option at the moment - advertising isn't *intrinsically* bad, but it can easily be abused.