There are only so many eyeballs, and right now being very sticky is an obviously viable strategy for dominance. Google didn't get into phone operating systems because they knew or cared much about them. They did it because their revenue base was under long-term threat. (Hell, Google is trying experiments to see if they can get in front of your actual eyeballs, intermediating your entire waking life.) And Facebook tried taking over people's phones for exactly the same reason.
Talk to the Googlers who have left over the last few years, and you'll hear very clearly that things have changed internally.