>> Perhaps you can write a tiny web app that loads instantly and still retains a full set of features, but most of the world cannot.

> I've long been skeptical of this line of thinking emanating from major thick client JS framework authors. I think they underestimate what people are capable of

Sometimes even when you can, you shouldn't. Any reasonably-sized organisation will have churn; new developers will have to ramp-up and it will take longer to do so on a hand-coded framework with all it's idiosyncrasies. I'll take Ember over Random Jim's framework, even though he is technically brilliant.