My theory is Google was never setup to maintain such a thing.
I think an operating system running on customers hardware requires quite a bit different, more stringent, responsible approach to development and release process. Microsoft seems to have it (albeit with their own flaws and in recent years they went rogue - when they fired their testers, shoot it was almost 10 years go).
Google is not setup in same way and internal incentives are not like that, judging by hoard of messaging apps. They are simply setup to make very short projects that do not require long-term commitment. When people move on, projects get abandoned, neglected and killed. Their incentives structure is like that. It is one thing to change a webapp willy-nilly and another thing to change and support code that you ship to millions of devices you know nothing about.
During 90th Windows had a lot of growth problem that Microsoft was figuring out, now Google's doing the same with Android but I don't think that they will succeed unless they change their incentive structure.
Now having said that about Google, one has to admit that it is _vast_ and there are a lot of different teams and I suppose there are plenty of teams that work in different way. But still, they can't be shielded from corporate overall culture.