Because ASCII minus instead of dash looks ugly. It's like using zero instead of "o".

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.

It looks aesthetically nicer. It was also a bit of a signal that someone took pride in their work and so helped that way. It's a bit like whether your tradesperson cleans up after themselves. Technically sweeping up the dust after installing a kitchen cabinet doesn't actually mean anything for the quality of the kitchen cabinet installation, but in practice putting the effort into the presentation correlates with putting the effort into the actual work.

An emdash means something different than shorter dashes

https://www.merriam-webster.com/grammar/em-dash-en-dash-how-...

i mean why use punctuation or any capitals at all, why not just blast words out in a stream of consciousness so readers know how yr thinking why even bother with speeling things write

Just because you don't care to use the proper dash doesn't mean everyone else doesn't. People have different levels of caring about different details. For the sticklers, there's even a special code point for ellipsis, … rather than .... (Four being correct, as one is to end the sentence.) Personally I'll just skip — entirely unless I'm in a trolling mood, though “sometimes” the right quotes are worth using. Special characters are easy to type on a phone soft keyboard, taking a long press on the relevant key, or if you're using any other advanced input system, so they shouldn't really be considered to be the mark of LLM input.

The real trouble is that people doing engage with the substance of the post anymore, and just shallowly dismiss a post as being vibe written, as if that makes any points raised invalid. Anti-intellectualism's always been cool among a certain crowd. Shame to see it spread but ah well, the propaganda's working.