That, and during the brief window where G+ had the most hype and the best shot and getting mainstream, which also happened to be right when Facebook had just recently made some pretty egregious privacy fuckups and pissed everyone off... they very strictly limited who could get an account. I forget the exact timings but it was basically impossible for a typical prospective user to get G+ until around 6 months after they had actually rolled it out. What the fuck, guys?

Then when they finally opened up registration no one gave a shit anymore.

I guess maybe they were trying to mimic the thing with Facebook where you initially had to have a .edu email in order to get a Facebook account - but it's very debatable whether Facebook succeeded because of that or in spite of it.