If someone disables JavaScript, the entire Internet will break for that user. So, no, BackboneJS and other frameworks like Angular and Ember are moving us forward by taking what used to be a browser language reserved for snippets and stupid animations and allows us to organize it in a collaboratively-friendly way for scalable user-friendly applications.
Keeping as much load on the client is where JS applications really shine. There is no need to force the user to make unnecessary http connections to your server and have your server do the work when the same result can be had without.