In the early days Usenet propagation was slow and haphazard because the communication links available were very limited. Nowadays I can post a message on one Usenet server and it appears on other servers in a few seconds. So coherent real-time conversations are no problem.
On the other hand, with a long-running discussion, HN, Reddit, etc. still have no way to see what messages are new since you last looked at a thread, something which Usenet clients have always done and still do now.
Usenet is a system so bad that "posting a message on a Usenet server and having it appear on other servers in a few seconds" sounds like an achievement. And: both those other systems have reliable ways to see all the new messages on a thread, unlike Usenet, which couldn't even guarantee that you'd see all the messages, let alone in order.
I was a Usenet systems engineer (regional ISP operator, INN hacker) during the heyday of Usenet, and a dedicated user in that time as well. These rose-tinted views of how well Usenet worked don't fly for me at all. Reddit is actively, materially, multifariously better than Usenet, and Reddit is not the state of the art.
I had tried this site a year or two ago and found it unusable then, but it seems greatly improved now. I found posts as old as 1982, but recent coverage seems to stop around April 2022. Crucially, it supports full-text search on posts within a specific group - something which my own site https://newsgrouper.org cannot do. I find the user interface a little awkward, but it does now appear to be a really useful resource.
As I said, the user interface is awkward. You need to select the "Content" checkbox when searching for Posts. E.g. to search for "deadlock" within comp.lang.tcl, start with https://usenetarchives.com/index.php?s=deadlock%20ingroup:co...
then select "Content", unselect "Author" and "Subject" and click "Search".
I have a Tcl Improvement Proposal (TIP 676) currently being voted on which introduces an alternative compact form of calculation. The implementation uses a Pratt parser: https://core.tcl-lang.org/tcl/file?ci=cgm-equals-command&nam... which directly generates bytecode rather than creating a parse tree.
You might be interested in https://newsgrouper.org - my web interface to Usenet, text-only. The site is implemented in Tcl, but only needs a web browser for a client. Some Android users find it preferable to the available native clients.
Here's mine: https://cmacleod.me.uk/ - I'm a retired programmer, my site has links to various projects, mostly in Tcl, some Javascript or C, also old blog, etc.
Note: when posting a link to an article on Newsgrouper it's best to use the "Permalink" at the bottom of the article. People clicking that will get straight to the article without needing to login as a guest. The permalink for this article is: https://newsgrouper.org/%3C10jcmri$l9u0$1@paganini.bofh.team...
On the other hand, with a long-running discussion, HN, Reddit, etc. still have no way to see what messages are new since you last looked at a thread, something which Usenet clients have always done and still do now.