I think the performance issues tend to come when you have a lot of controls and associated bindings via angular on a page. The use of jQuery (improperly) tends to exacerbate the issue. Most people won't come across the issue, to be honest. Facebook has a lot of points of display and interaction on their pages, so it quickly becomes an issue. Not to mention the simpler flow is easier to track.

I do find that the flux model makes more sense to me. Flux is a set of best practices, they use React for the rendering/view portion, and since their talks there have been several implementations of the workflow. Some using Ampersand or Backbone, others implementing their own pieces. Now Facebook has been releasing their own implementation...

It's all pretty interesting.