I think people who care about correctness and also read a lot automatically see the difference and it seems (and is) technically incorrect to use a hyphen where an em dash belongs. That’s really it. Kind of like you wouldn’t just leave out the apostrophes in your writing even though in most contexts they are not strictly necessary for comprehension.
Leaving out apostrophes isn't the same though, is it? If you leave out apostrophes you have syntactic effects while a (sortof)dash is still sort of a dash?
Its not exactly the same, of course, but its pretty analogous. It’s a minor, technically incorrect change that doesnt change meaning or understandability most of the time. Ive left out a bunch of apostrophes in this paragraph and Im pretty sure nobody will have a hard time understanding any of it. Yet it would bug me to actually write like this.
I don't know how this works nowadays but when I got taught to write (the pencil and paper kind) and specifically when I got taught syntax, it was "if you want to introduce a clause that explains or expands upon something that precedes it, you draw a small horizontal line" no mention of special chars, Unicode or whatsoever. So why is it so special other than being authors fancy?
