You missed the primary issue OP mentioned, which is that ASOP is becoming a smaller and smaller part of the entire OS, and there's an ever-increasing amount of work needed to make it work on a real phone.

Yes and also more and more apps are blocking custom ROMs.

Even the McDonald's app is doing it now (I know, you're not missing much there but still...). It refuses to launch if it was installed by any method other than the official play store.