Ask everyone again. This was true a long time ago (long time being, like, 1.5-2 years), where the Facebook app was so slow and so crashy (and the API down so often) that it was mostly useless.
Facebook is, IMO, one of the gold standards now for large-scale iOS app building. I had the pleasure of hearing one of their people speak about this a few weeks ago and they're very much at the forefront of iOS engineering.
I've been using the FB app since it arrived on iOS. At one point it was a decent app, but it is far from being the gold standard. The last few updates have just introduced more bugs and lag to the experience. Lately I don't even know if I clicked the 'comments and likes' text reliably. You can't tell if you missed the ridiculously small hit target or if it is just taking the usual 3-5 seconds to give you any kind of indication it is doing anything. That's just one example of a frustrating experience, but I consistently have others—zooming and panning pictures randomly closes them, likes sometimes never show up, my own posts won't be visible on the phone, only on the web, etc.
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.
