As others have been pointing out feverishly on Twitter: the problem wasn't them betting too much on HTML5. Their problem was developing piece of shit apps that happened to use HTML5. They tasked amateurs who didn't know what they were doing into building a hybrid native app container which in turn embedded HTML5 content. Plenty of other developers (Instagram and LinkedIn come to mind) have figured out how to do that right, and in a way where it is seamless to the end user and for all intents and purposes feels exactly the same as a native app.
I'm not saying that it's an easy problem. You have to find the right balance between which components should be native or not. It's clear from the other problems that Facebook's been able to solve that they know how to hire top-notch developers. They just failed to do so for their mobile efforts, which just reinforces the stereotype that they don't "get" mobile.
Yes, and it is more used than their mobile app. Were you referencing their use of html in their app? That is an entirely different issue, but yes they also did that.
