I'd think most roll their own apps, framework or no framework. But yes, there should be one alternative for no framework and another for native development. To your other point, if you look at frameworks like jqMobi and a cpl of others there really isn't much bloat. You can further remove functionality/widgets (or just don't call plugins) you don't need in your project. You mentioned the FB and Twitter apps. Thing is, it's not less code there, just smarter code and better design. They employ some gifted and smart ppl.

Agreed. Mobile web apps should be simple, fast, and to the point. Most of these frameworks are redundant if you know DOM and CSS appropriately.