I don't believe the ad stated that everyone could dive a rebreather. Although, it's NOT that complicated. Remember: Stupid people do stupid things. Stupid people do stupid things on open circuit
as well as rebreathers.
If Joe Blow goes goes through an agency with 8 dives, he's not going to get trained or certified to dive a rebreather immediately. For well regarded agencies, you need the equivelant of at least Advanced Nitrox to get through the rebreather door. Other than that, you're not going to stop someone from buying a used rebreather and going down the DIY route.
Oh, and don't look now but we have a
Rebreather forum on this "recreational" site.