I agree completely. This is how I started. I'm not a coder. I can do html but thats it! I had some extra time on my hands and had played pbbg's for a while and I just started putting together all the things I had been thinking of for years. Things like "Why can't I do this?" and "Why does it have to be like that, why can't it work differently?"
My original game document is 39 pages, single spaced. Nearly a year after the game's release and we've added all but one of the features in it. Lots more planned, but I use smaller docs focused on a single update. I used Word's headers and the Document Map to help organize it all.
For any would-be designers I would GREATLY suggest checking that out. I have my headers short-keyed Ctrl+Alt+1, 2 or 3 for headers 1, 2 or 3.