Marketing is a huge part of the success of a new paradigm. App.net was "marketed" with a practically blank home page ("one login many applications" - which applications?), and a nondescript niche Twitter clone on one of its subdomains.

It had no chance at all. Where was the evangelism? Where were the presentations, demos, and the other useful apps built on this platform?

I'm a developer and I did hear about App.net when the buzz was at its peak. I remember going to their home page and wondering "wtf is this?", then checking alpha.app.net on a couple of occasions, finding nothing of interest and that's it.

That wonderful arrogance that the world will care about your project because you're somehow "right" has killed many tech efforts and will kill a lot to come yet.