That would be because ‘real’ VR requires quite a lot of work. Let’s start with that there are way too many smartphones out there and it’s probably a nightmare to create AR app that would be compatible with most. Next important thing, to make things work like a charm triggers have to be set up in place where games are played. All in all, it’s still too complicated and it can’t be charged accordingly as most mobile players are not ready to pay more than few bucks for a game. Maybe AR+ will change something but that’s still far away.