> Let’s use Google+ as an example. It did shut down and still not all wounds have healed yet

Despite (and in contrast to) the absolute massive marketing effort that Google put into Google+ right from launch, it never achieved mainstream success as anything other than an OAuth login tool. That doesn't mean nobody used it, but it was always niche.

It's not a proper comparison for Twitter or Facebook, which grew organically and are both mainstream successes as social networks.