Ethics

Regardless AOSP _is_ Android and it is a functional open source mobile phone that you can actually go out and use just using open source code. Sailfish is not.

The closed source bits are typically Google add-ons (optional) vendor add-ons (avoid avoid avoid) and closed source drivers (which depend on the phone/device you are using).

People have tried before to make phones and mobile devices using stuff from 'standard Linux machines'... and they ended up being a terrible match and extremely detrimental to getting a working phone. It's not just technical, but cultural and waffling between QT and Gnome-based environment is a perfect example of why it hasn't worked out.

People really need to study Android and understand why it was successful (example: why the traditional Unix model of users and applications suck for modern ways we use computers) while all the other efforts to build Linux-based phones are not. Otherwise it's just a waste of time if your goal is to have a product that appeals to a larger audience. (if your goal is not that then it is much less of a problem)