Most people who want to write a long document use a word processing program, such as Microsoft Word or OpenOffice. The formatting is obvious, and what you see is what you get in a very literal way. Even a person who fears computers can write a novel with a word processor, and they often also know how to email that novel to their friends. This is assuming that they know how to write, of course. Some people are terrible at writing, such as myself.
But publishers cannot directly work with word processor documents. They have their own standard, PostScript, from which they can easily print properly formatted pages at whatever size paper the book happens to be, and any formatting, included pictures, or special considerations will be retained even if other factors are changed. (I will ask a publisher what these factors are, since I can't think of any other factors that would mess with the formatting.)
Both PostScript and most word processor formats are well documented and standardized. Therefore, it is possible to write a program that could easily convert between the two, and furthermore, possible to produce a webpage form that accepts a word-processed document, converts it to postscript, and offers both up to a publisher for consideration. Publishers reject most of the writing they get, on the grounds that most writing they get is absolutely terrible and would not sell very well. However, stripped of this technical limitation, I believe that worldwide literary output would increase. This may also increase worldwide literacy rates.
For best results, the conversion program should be open source so that anyone may use it.