Why not? Actually, there's no reason.
Well, csSPLIT.js will grab the DOM, collect all the classes and then try and load a CSS file for each of the classes. This mean, if you have a class
.block you'll need to place a CSS file called
assets/css/ - everything placed there will be included.
You are _maybe_ right! It is indeed insane, however with HTTP 2 this scrip will rock! With the HTTP 2 Protocoll, all the old stuff like compression and combining files will be outdated.