You do realize that Android requires a Google Account on most devices to function? (not talking about custom ROMs here).
Also, Android devices have outdated Linux kernels are are only updated once or twice before EOL.
Also, Android devices have outdated Linux kernels are are only updated once or twice before EOL.
And it'd be trivial to compile the latest kernel and load it on your device. Someone who really cares and needs features or fixes from a newer kernel could do it if they wanted.