They already have too much of my online attention. Sharing anything except my searches with them is a non-starter. It doesn't matter how well implemented the service is. Because it's Google, there's just absolutely no way I'm using it.
I've started moving away from their search, too, now that they decide for me what constitutes "mobile friendly" and what doesn't. Fact is, some "desktop" work better on my phone than a lot of the "mobile" sites do.
I don't want a nanny-search moving the things I'm looking for down the page. Just give me what I searched for, nothing more, nothing less, no "judgment" about what I want to see.
FWIW, I think it was the "single real name policy" that actually killed Google+. At that point I stopped commenting on YouTube, stopped using Google+, and in fact just stopped "signing in" to anything at all Google.