[retro212]

disclaimer: I work for Bitovi, and I'm a CanJS core comitter

Short answer: yes, people do build real apps with these frameworks.

I stumbled upon JavaScriptMVC (CanJS was extracted from JMVC) 4 years ago when I was building application with a lot of front end code, I think we had around 10k lines of JavaScript in various modules. Trying to build something like that without a framework was a huge pain, and JMVC helped here a lot.

In last few years (after I started working for Bitovi) I worked on pretty big enterprise level applications, and besides being able to build things in cleaner way, a huge plus was ability to allow less experienced developers (from the companies we did consulting for) to implement stuff with familiar structure and without needing to care about memory leaks, zombie events and similar stuff.

IMO CanJS is the best framework currently available, but I'm extremely biased. In the end I don't think it matters which framework people choose because they will get a lot of value just by using any of them.

That said, I would never again use a DOM-centric approach for frontend apps. Live binding is a huge game changer and data centric apps are (in my experience) less buggy and get stuff done with less code.