All that is true, but the primary problem with Google Plus was the network effect. Whenever I logged into Google plus, most of the content from friends was basically “cool, so this is Google plus” and nothing else, because everything at the time was on Facebook. Later Google started filling my feed with stuff from strangers because there was no organic content from people I actually cared about.
If you can’t solve the chicken and egg problem of engagement then nothing else really matters.
I'd probably have signed up if it were not for those two issues. Step zero in breaking the network effect is not to piss off those who might join despite it.
If you can’t solve the chicken and egg problem of engagement then nothing else really matters.