Funny. I have a brother. We have at times lived together, went to the same school, and after not living together, lived on the same street. A couple of times, one or more credit bureaus decided we were the same person and silently merged our credit files. Not a nightmare per se since we're both fiscally (mostly) responsible, but we generally find out how incompetent the bureaus are when we're trying to make some very large transaction (I was trying to buy a car, he was trying to buy a building for work) and suddenly get "why do you own 2 houses, a bunch of cars, and you're apparently a bigamist". And then we had to scramble to untangle the whole mess. Lawyers were involved. The bureaus do not care in the slightest.

It's not "if you're not doing anything wrong" you need to worry about, it's "what will they make wrong down the road to trip me up" you need to consider.

Up til 20 years ago there were a surprising number of ATMs still running OS/2; NCR and Diebold supported old machines for a long time. Especially small market/small regional banks wanted to get the absolute most out of their capex investment. Over the years, I've worked with a couple of those dead-enders on different GRC projects, mostly because I'd actually seen OS/2 before. AFAIK, those vendors stopped supporting OS/2 in the 2000s; I'd be very, very surprised if there were any left now.

I you're interested in how a very "not Unix" operating system is architected, I really recommend Deitels' "Design of OS/2". Very interesting.

Lotus users were just as fanatical.

They were, and Excel users are just as devoted if not more so. We had many people return their shiny new mac because Excel on MacOS is not exactly like Windows. And they were mad about it.

Lotus on a Sun? Why not.

How about 1-2-3 on SCO Unix. And Wordperfect. We had a salesrep (VAR) back in the day who made some scratch in the local legal market with the pitch "why give every secretary an expensive PC when you can buy one PC and a bunch of really cheap Wyse serial terminals". Our support folks came to really hate that guy (start at "you were using a typewriter 5 years ago...now you get to learn the Unix CLI" and it only got worse).

Oh sure...some companies had their own setup. I think one of the disk drive manufacturers had their own BBS (Western Digital?). But I think most companies looking into this kind of service saw the Compuserv infrastructure (in particular, all the ways to access it...dial, X.25, leased line, etc., with huge numbers of local PoPs) and said "I'll take that because building ourselves it would suck".

And...there was a time between this and "Internet for all the things", when for consumers, AOL was the place to get drivers and such. But that's an even farther digression from the BBS topic (other than to point out AOL started out with BBS software).