Instead, HTML allowed one common language to proliferate.
HTML5 and its advocates believed the same thing would happen in the mobile Internet. Mobile developers wouldn't want to do all the work to build different versions of the same mobile apps. So they'd all opt for HTML5 as a programming language.
Facebook was very supportive of this philosophical view. After all, it didn't have a dog in the mobile OS fight because Facebook was just an app running on Android or iOS. As well, Facebook wanted to minimize the work required to keep up in servicing the various mobile apps. So, Facebook chose to write its apps in HTML5.
With that one decision -- which makes sense when you think about the various pluses and minuses of the different options -- it made its original Facebook app perhaps the most hated mobile app ever.
It was slow. It was buggy. It crashed -- a lot. I don't pay that much attention to reviews of different apps in the App Store, but the low scores for Facebook's and the terrible comments were remarkable, especially considering that it was one of the most downloaded apps on the store.
What's really interesting in reading the discussion in Branch about this bad decision is how long it takes to really undo a bad decision.
For the first year or so after making any decision like this, it's still early days. If there were users who complained, it would be easy for the Facebook management (who naturally wants to think they made the right decision) to say to others, "It's still early days for HTML5, so we don't need to worry." Or they might have thought, "Well, mobile hasn't really taken off anyway, so we can wait."
In the second year after a really bad decision, there were likely some doubters on the management team -- but they would have likely had long debates with those who probably still thought there was no problem.
In the third year after a really bad decision, when people really start to complain, that's when any management team has to look itself in the mirror and admit it's wrong. But even after they do that, there's all the work required to undo a bad decision.