First, there were printed books. Sure, you can buy everything for a dollar or two on paperback, but, for some reason, people prefer a $45 hard copy that weighs a pound or so and hints of the real value of the book.
Then, user manuals did just the same. OK, 20 years ago there was no desktop-printing. but the printhouse could print single-font single-style $1 copies, or go for the good old $45-1lb copies. They ship more expensively, demand more personnel, and the customers get a sense they are getting real value for their money.
WYSIWYG text editors mimicked this approach. Why send a TXT file to your good-old printer if you can send a DOC file to the color-printer over the cubicle? It make you feel you write beeter content, it costs much more and it creates jobs.
I used to work like that myself, I admit. I mimicked book layouts I have never read myself. Then, I switched from Word 2000 / 2003 to RoboHelp X5. Then, I have to move on to a new tool, and the printed layout looked fine, but totally different from whatever I knew before.
The content was readable and accessible. I used up to 10 styles for the entie user guide. Sure, I couldn't create 5 types of bullets and another 4 types of notes.
The readers could still find what they were looking for and my work became way more simple.
I don't take credit for dropping WYSIWYG. But it dissapeared, and I never missed it.
At that point I started experimenting SocialText for my documentation projects.