Earlier quoted context omitted.
The problem with your theory is there are a TON of evidence it is not in any way reality. For example, if their primary motivations were Preventing Monopoly status, and feeding their AI Research they would be embracing open standards, Federation of services, and a whole host of other things they have rejected the last decade or so. They would have never Killed Reader, they would have never taken Hangouts off XMPP, th…
A social network is better when almost everyone are on the same network like it was with facebook. Google avoids having a too good social network to avoid becoming dominant. If Google provided a good stable API, people may never consider going to concurrence. By pissing off some users, Google stimulates competition and avoids becoming a "public service". I think this reasoning explains well Reader, XMPP, their droppe…
Launching a bunch of terrible and failing copycat projects and closing down actually useful "niche" projects sure helps with not appearing too dominant, but it does nothing to help feed Google's AI.
It also does nothing to prevent Google's competitors from becoming dominant and getting locked out of important data sources like social interactions (Facebook) or product search (Amazon).
I agree with syshum. Supporting federated, open protocols would make much more sense. It would make Google appear benign while at the same time granting them access to a lot of data and help keep competitors at bay.