Apparently Facebook's iOS engineers weren't that excellent (I mean, really relatively speaking), so comparing their old Facebook effort to a well-made web app's is not telling.
Plus, the Facebook app is way different now. I don't see how it'd be possible for them to implement web-based chat heads without killing the performance (even on my iPad 3 it isn't 100% smooth). Lots of times these clever design concepts cannot be implemented on the web because of its relative performance drawback.
http://www.tuaw.com/2013/03/05/whys-facebooks-app-so-much-be...
Plus, the Facebook app is way different now. I don't see how it'd be possible for them to implement web-based chat heads without killing the performance (even on my iPad 3 it isn't 100% smooth). Lots of times these clever design concepts cannot be implemented on the web because of its relative performance drawback.