Because average people are not just zealot crazies. Compromises and spectrums exist.

AOSP is still the best Linux-based environment for consumer use case from many aspects. It handles hardware better than GNU-based desktops, it is more secure, it supports things like HiDPI screens better and it has a stable API to write applications against and many people and organizations did so (you can still use Android 4 apps).

AOSP has strong Google influence but it is possible to use it without feeding data to Google.