This is a variant of survivership bias and says effectively nothing.

Just because things have gotten more complicated and people have used them doesn't mean that people will start to use any complicated thing.

For example:

Google+ / Google Wave isn't an alternative to email if my grandma can't use it.

GPG isn't an alternative to talking in-person communication if my grandma can't use it.

... etc

Yes, you have valid examples where things that are relatively complex did become popular, but there are many many more examples of things that were more complicated and failed.

Just because scuttlebutt is complicated is not a reason it will succeed, but is indeed a valid reason it might fail.

My Grandma definitely skipped from a corded phone to an iPad with Facebook and right over email. It's still too complicated for her.

And yet billions of people use email. Goes to show the grandma argument is not very useful.

Most of them using an interface like gmail, which unsurprisingly looks a lot like (facebook) messaging.

Sure, thinking about user experience and designing user-friendly UI is important. But multi-million dollar UI and the ability to scale without losing performance (due to deep pockets) are the only reasons to use FB, goOgle or any of The Stacks. Once more UX people and graphic designers start working on decentralized, free code apps, and organic growth via community-hosting (userOps) allows them to scale as well as corporate server farms, where does that leave The Stacks?