The problem is that a number of users that would make a dedicated startup quite happy, doesn't interest google - "low growth or low interest" is a rather high bar for google. Google Reader was huge, just not google huge.

EDIT: Why I think this, is because I'm annoyed that all the big companies want one of what all the other big companies have - music locker/streaming service, home automation platform, tv platform, freaking VR goggles. One does it, the rest have to get one too. Then it's forgotten in a couple of years. (Helpouts was part of the Hangouts push, and now that the push is over, it's forgotten.)