This would be my guess as well. I worked on a ExtJS project (v4.0.7 or so), we didn't use the sencha build tools, but when I started there we had a bash script which was a 7 iteration sorting "algorithm" that used grep to try and match the `requires`, `extends`, `model` properties to determine dependency order. It too also uses commented out code or documentation of usage, as they were the first lines it saw. I still do not understand how it worked for so many years. The first thing I did was build a deterministic dependency ordering build tool using esprima.

It didn't require it; it was optional depending on how you used ExtJS. In a project I worked on we simply had the minified, master extjs.min.js file included and then we simply referenced and used that.

I don't remember how the build stuff differed but it wasn't required (though I'm sure there was a benefit to using it).