I have an anecdote for that. I work at a bank and in the past two years we've built a front-end for investment banking using BackboneJS and some other frameworks. This application has close to 200 views, 26 routers, and probably 200-300 models/collections, totaling at about 30K lines of front-end code. You really have to use RequireJS or Browserify for a project of that scale, or even for any non-trivial project.

New projects (and the one I'm working on atm) are built in AngularJS, which has a built-in dependency system. We're not going to use RequireJS as a script loader anymore; in practice, it'll just load all the files on application load, which doesn't really add anything. I like Angular's simple approach of just loading a bunch of scripts using script tags. The existing application is going to get rewritten in Angular too, it's expected that it'll need a lot less code.

100,000 lines of JS is best divided into smaller parts.