#I don't actually know how unique to Nietzsche this kind of structure was but he's the only one I've actually read who does it I think

[nohoperadio]

The post feels like a very natural unit of literary production to me: one to three shortish paragraphs expressing an idea, generally in quite a casual style, without necessarily any claim to profundity (there are other types of post but hopefully the vague genre I'm talking about is recognizable. This post is a post if you need an example). It feels well-suited to the shape and size of everyday garden variety thoughts. Bigger and clumsier than an aphorism, smaller and looser than an essay. Just some thoughts being recorded with minimal polish beyond what's needed to make them coherent to someone else.

It feels like, if you gave an intelligent species the gift of writing when they didn't have it before, this would be one of the first and most obvious genres they'd invent. But I'm not actually sure what outlets there were for post-like writing prior to the posting era; most things that got published had to be higher-effort than this, right? Or feigning to be high-effort at least. When publication requires non-trivial resources the bar for what gets published... well, exists. I would guess the writing we would recognize as post-like would mostly have happened in more private media like letters and diaries?

Actually now that I've described it, the pre-internet writing I've read that most closely matches the spirit of posting is... the books of Nietzsche?? Specifically the ones that are like The Gay Science where it's largely self-contained numbered sections that are each about half a page on average (but can be longer or shorter), and which vary quite a bit in style, subject, degree of seriousness and degree of "personalness", in a way that feels quite bloggy? I mean they're obviously better written than most of your dash, I'm not trying to play that annoying game where you claim that this highly revered impressive thing is actually no better than this other low-status minor thing. But purely in terms of form, I think there's more isomorphism between us and him than between us and most other historical antecedents I can think of.