Mind, this isn't a 100% fair review, it's not an in-depth comparison or anything like that. It is, however, the "first glance evaluation" you'll probably get from any Flash game developer who's wondering whether they should switch to HTML5+JS.
I'm not saying we should just give up and use Flash forever and ever. I'm trying to explain why HTML5+JS is not a mature game development platform yet.
On the other hand, I'm pretty sure DOM doesn't provide a boilerplate game loop. It might sound trivial, but sorting and linked lists also sound trivial and you don't see people reinventing them on a daily basis either.