CompuServe. AOL. Both dominated social media so much that anyone new had practically no choice but sign up because everyone they knew who was on any social media was on there.
Wasn't long ago here on HN we were bantering about Facebook disappearing because everyone was leaving in droves.
There's always a Facebook-shaped niche. It used to a CompuServe-shaped niche. Then it turned into an AOL-shaped niche.
But it's the same niche, for more-or-less the same user profile.
And it'a a very vulnerable niche. FB may seem unstoppable at the moment, but it really isn't.
The number of ways it could be replaced is non-trivial.
Zuckerberg knows this, hence internet.org, which is really just a way to promote lock-in in the developing world. But that's a lot less useful than it seems if FB loses traction in the developed world.
Wasn't long ago here on HN we were bantering about Facebook disappearing because everyone was leaving in droves.