RMS is extreme, but your questions don't seem that hard to to imagine answers to.
1. Why would we want to do that? What problem does creating the next Microsoft solve?
2. I have never heard him claim this. Free software means that you have a right to troubleshoot and resolve problems yourself if you want... not that diy is the only option
3. Why can you see one, but not the other? Some of the best documented software is foss. For example, Its hard to beat Emacs documentation.