On top of the reasons stated before, DotA's code is both long and obfuscated. If you open that 6.67c map script up, you'll see a novel worth of code, with all manipulable names converted into seemingly random blocks of all sorts of letters of the alphabet. There will be no indenting or breaks.
If I wanted to look for certain spells in DotA's jass file, I could probably find them given time, but that's because I would already have a good idea of what I was looking for. If you're trying to figure out how some kind of effect is accomplished, I would recommend looking elsewhere. Like a Warcraft III mapping forum.