Yes, Backbone is an extremely small library for what it provides (less than 1500 lines of code with comments), but you still might not want everything it gives you.
With custom builds, you could use the Backbone Events class object as a standalone pub/sub solution, or only use Backbone Views to organize all of your app's event handlers, or use Backbone Models to store all of your applications data client-side, etc (all while minimizing your file size).
Backbone is incredible, so I wanted to make it even easier for people who aren't completely sold on using it, to only take what they want/need.
No, anyone could have easily done this. It took me about an hour. I looked at the Backbone codebase and split up all of the Backbone Class Objects into their own files.
Backbone by default is not set up in a modular way and instead heavily uses local variables all scoped under one Immediately Invoked Function Expression (like most libraries). I had to make a few changes to the Backbone core to remove these local property dependencies so that they could be split into several files, but that was it.
My changes were small enough to minimize the risk of introducing new bugs. I also made sure that my modularized version of Backbone passed all of the Backbone unit tests.
I'm not sure. Hopefully in the future Backbone will provide this option. Until that happens, I will continue to support the project.
Unfortunately, I will also have to upgrade my code to match the changes.
You can find all of the Backbone modules inside of my Backbone Fork.
I used DownloadBuilder.js to make the custom build. I also wrote that library (shameless plug)