> The reason why no one runs AOSP is because the phone market rewards differentiation.

This is what empire-building middle managers say to rationalize their boondoggles, but in actual fact most customers can't even tell the difference between two different vendors' Android skins, definitely can't tell the difference before they buy one, and the way they actually differentiate phones is on real hardware differences that show up in the specs like the camera or performance.

The hardware company's idiosyncratic fork of the software is irrelevant at best and annoyingly irregular in the common case.