I get your point about angular -- I tend to think it has a particular use case in mind and does really well for that one. However, my point was that backbone doesn't give you much more than plain javascript itself -- let's not expect to abstract everything away compared to one of the full service frameworks. YUI, however, is aiming to be a full service framework. What is the additional benefit?

Now, it's possible that YUI would show itself closer in terms of LOC/complexity to the other frameworks in a larger application. But looking piece by piece, ember and angular just seem to do things more efficiently, more clearly than YUI. And that was my point when discussing LOC.