I don't understand how it solved the problem with fake reviews. I think you need a google account to even have google play working at all so if I'm going to write bogus reviews I can still make it a Google+ account and use whatever name, it isn't like they're checking.
Google knows who you are if you're using an android phone (they DO know a lot about you, think, they have your location, your IPs both from inside and outside the network, your IMEI, IMSI, possibly your phone number, your address book, your email, even before you start giving them credit card no, pictures, documents, etc). It's not hard to weed out the non-users.
The only problem they had was that nobody was using Google+. This is why they're pushing it to play store, youtube and who knows where else too.