While that’s technically true, it does use a severely cut down version thereof which is worse in every way: it only supports paragraphs, code blocks, and emphas

While that’s technically true, it does use a severely cut down version thereof which is worse in every way: it only supports paragraphs, code blocks, and emphasis so the ability to format is extremely limited but the emphasis can still screw you over, which requires an explicit preview (or posting) to notice. And I think escaping emphasis was only introduced somewhat recently? I do remember that for the longest time you basically had to trick HN into not breaking your comments by using a different character in stead.