Each of these has a story behind them. Some were getting DOD money, so of course they joined.
Spdcc is Steven Dyer, a big name in Usenet and always on the cutting edge… also openly gay which was rare then.
The list shows who the big computer vendors of the day were: HP, IBM, DEC etc. none of those companies exist any more (just kidding… but not really).
1986ish was when the concept of a workstation was new. The list embodies that movement. (The MIT project that galvanized a lot of that is an an interesting story). All involved have domains.
So many of these companies are gone. Each has a story and a lesson to learn.
Who isn’t on the list is interesting. Microsoft. They ignored the internet for years. AT&T ignored the internet but someone in R&D registers the domain.