Gessner here seems to have the “notes so atomic they’re physically disconnected” aspect of zettelkasten, but not the pointers mechanism. Ashby’s example does seem to have the whole spirit, though I could see someone more persnickety than me objecting to how a lot of the notes with properly distributed pointers aren’t in the physically disconnected mode (instead in notebooks), and the physically disconnected part (from what I’m reading? The index cards?) is more like the Syntopicon / index part than independent observations.
But!
It seems unnecessarily hostile to me to claim that people are “idolizing only [Luhmann] because of our availability heuristic bias” when there are real aspects that excite people about the system Luhmann used that just aren’t present in Newton’s indexing. You don’t have to be making an idol out of Luhmann to find it cool!
I can’t speak to Leibniz because I can’t actually get the researchgate stuff to come up on my computer, which seems like less of an availability bias problem than an actual availability problem.
The essence you think is important about zettelkasten may be present in some of these, but people who find different aspects to be the compelling part aren’t necessarily ignorant or to be condescended to. And outside of claims of innovation, when it comes to the attention various note-takers get, are we blaming folks for not finding “write out your notes and then cut them up” as inspiring as someone with an accessible real-world history of use in a setting closer to our own?