Given the costs of that access and the costs of the computers. It was both a very small and a very specific type of person that was accessing Usenet at the time.
As of 1995, total worldwide Internet usage (then largely in the US, though also Europe) was 16 millions. As of 2019 it's 4.5 billions.
https://www.internetworldstats.com/emarketing.htm
(From an earlier HN comment: https://news.ycombinator.com/item?id=21783812)
Brian Reid's Usenet Usenet usage reports as of 1988 reported about 140k active Usenet users, from a population-with-access of about 880,000.
Usenet was small.
(Some of these stats also cited in in one of the links (which I wrote) from TFA.)
I did eventually get to use a 2400 baud modem though, and even ran my own BBS for a while. Fun days.
https://ryanfb.github.io/etc/2015/02/23/early_usenet_history...
Getting it off piles of tapes and onto that thumb drive, however, was a large task:
https://www.joe0.com/2019/02/17/converting-utzoo-usenet-arch...
In 1988 Compuserve (more than 250,000 subscribers) was charging $11 per hour, The Source charged $8 per hour, Delphi charged $6 per hour, and BIX was $9 per hour.
Eleven 1988 dollars would be about $23 today.
That in itself was a significant enough barrier to entry for the general public. Most people prior to Eternal September were unaware that the internet existed, or falsely believed it could only be accessed by university students. And outside of the G10 countries getting online was a major technical barrier.
On the positive site, I know of one intercontinental marriage facilitated by RAP.
I happen to have all three, and participated in Usenet just minutes ago.
You might want to delay your Usenet death proclamations by just a little.
Most ISPs provided usenet access just like they provided an e-mail address at the time. So it was no more difficult to be involved in usenet than it was to have e-mail.
In modern terms, usenet would be reddit if it was distributed (so anyone willing to set-up their own server could run a node and let people connect to it). But for end-users it was as simple as having an e-mail account and a client application on your computer.