I'd always heard that moving more and more functionality into play services was their strategy for end-running the carrier fragmentation problem.
Though Google have fixed it in such a way that's benefited them by consolidating services and potential data collection for revenue raising.
I've not used anything but a Nexus of Pixel in years. But carrier fragmentation (and with it, the difficulty for OTA patching!) is a much bigger risk to the Android ecosystem and it's uses than closed source code.