"An english speaking person able to work entirely in ASCII" is a single use case that still leads to that complexity: we have emojis because people started drawing things with ascii characters. More recently, we have fonts for coding allowing for ligatures, and they're popular among a significant number of your fellow english speakers who could work entirely in ASCII.
Even then, much of the complexity outlined in the article still appears when you consider variable width fonts--really, your use case is english user, using only ASCII in a monospaced font. Variable width fonts need kerning, and to accommodate changes in glyph size based on italic or bold variations. Also, English has ligatures like æ, so if you want to deal with older English texts you need them.
And then what do you do if you're working in English but need to discuss other languages, even just common European ones with accents?
So your use case is now english ASCII monospace user working who's basically just programming with their editor, and this is a very, very narrow use case considering the rest of English speaking/writing users who want to use computers in their own lives.
Now multiply all the complexity I've sketched out for every language on Earth spoken/written by some community that would also like to use computers.
Even then, much of the complexity outlined in the article still appears when you consider variable width fonts--really, your use case is english user, using only ASCII in a monospaced font. Variable width fonts need kerning, and to accommodate changes in glyph size based on italic or bold variations. Also, English has ligatures like æ, so if you want to deal with older English texts you need them.
And then what do you do if you're working in English but need to discuss other languages, even just common European ones with accents?
So your use case is now english ASCII monospace user working who's basically just programming with their editor, and this is a very, very narrow use case considering the rest of English speaking/writing users who want to use computers in their own lives.
Now multiply all the complexity I've sketched out for every language on Earth spoken/written by some community that would also like to use computers.