I don't mean this in a bad way, but do we really need another Javascript framework? Wouldn't author's energy be more useful when contributing to one of the existing ones?
Obviously the author thinks so.
The fact that frameworks are appearing at a ridiculous rate is also the reason people still feel compelled to make their own: the existing ones sometimes feel thrown together and flawed in obvious ways, so people automatically think about ways they could be better and try those things out. The result is progress (edit: sometimes the result is a bag of crap, but that's beside the point).
No, we don't need more frameworks. And yet that still isn't a good reason to stop building them, if for no other reason than to explore for yourself what goes into building one (if that's your interest).
With JS the restrictions and limitations of the system are different. People are coming up with creative and innovative ways to work with them. There's no problem with that, it a process that's ongoing in all software, and forever will be.
Also, "You" should really avoid using "They", especially when it applies to a broad group of people that you're making assumptions and judgements about. Maybe "You" have no idea what HTML5 apps offer (like portability)? I happen to think that html5 is going to be a major player in apps development, which puts me in your "They" camp, then again, I know what native offers - so I'm one of the many contradictions to your statement.