The problem is not the Internet but the author and those like them, acting like social network participants in following the herd - embracing despair and hopelessness, and victimhood - they don't realize they're the problem, not the victims. Another problem is their ignorance and their post-truth attitude, not caring whether their words are actually accurate:

> What if people DO USE em-dashes in real life?

They do and have, for a long time. I know someone who for many years (much longer than LLMs have been available) has complained about their overuse.

> hence, you often see -- in HackerNews comments, where the author is probably used to Markdown renderer

Using two dashes for an em-dash goes back to typewriter keyboards, which had only what we now call printable ASCII and where it was much harder add to add non-ASCII characters than it is on your computer - no special key combos. (Which also means that em-dashes existed in the typewriter era.)