FWIW, my observation of Google's app store policies over the last 8 years or so is that they simply trail behind Apple's policies by a couple of years. Google is constantly expanding their store policies in order to better vet who is distributing apps, restricting the behavior of apps, etc. and they almost always mirror what Apple has already put in place.

I would agree with you that Apple isn't the only entity that can provide that type of vetting process but it also seems clear to me that a vetting process is actually a useful and desirable service.