WYSIWYG means "What You See Is What You Get." If you want the title to be Courier 24 point Bold then that's what you see on the screen. If you are writing in a proportional font with proper kerning then that's what you see on the screen. You don't see a fixed width substitute.
This is what enables you to do proper typesetting and page layout for a document, and using a PostScript printer such as the Apple LaserWriter you could do desktop publishing [1]. Desktop publishing was invented by Xerox PARC but the revolution began when Apple made it available to the masses with the Macintosh and LaserWriter.
Apple didn't invent any of these technologies but they were the first to put them all together into a package for the mass market and made them incredibly easy to use. Suddenly, grandma had a tool she could use to write and typeset the weekly church newsletter from home, and even print it on her LaserWriter at home. If she wanted to do a newsletter like that just two years prior she would have had to hire the services of a print shop to do both typesetting and layout as well as printing.
She could still have used WordStar or WordPerfect and printed with a dot matrix printer, but that doesn't get you large, proportional fonts or layout.
This is what enables you to do proper typesetting and page layout for a document, and using a PostScript printer such as the Apple LaserWriter you could do desktop publishing [1]. Desktop publishing was invented by Xerox PARC but the revolution began when Apple made it available to the masses with the Macintosh and LaserWriter.
Apple didn't invent any of these technologies but they were the first to put them all together into a package for the mass market and made them incredibly easy to use. Suddenly, grandma had a tool she could use to write and typeset the weekly church newsletter from home, and even print it on her LaserWriter at home. If she wanted to do a newsletter like that just two years prior she would have had to hire the services of a print shop to do both typesetting and layout as well as printing.
She could still have used WordStar or WordPerfect and printed with a dot matrix printer, but that doesn't get you large, proportional fonts or layout.
[1] https://en.wikipedia.org/wiki/Desktop_publishing