We Ran Our Own Infrastructure

Another revisionist myth. SourceForge (the first forge!) wasn't "our own", nor was BitBucket (mentioned by author), or Gitorious (which was famously archived btw). or sourceware, or ...

I guess we can call ftp servers like the gnu ones "ours". But that's about it as far as where congregations of relevant projects lived.

Did some projects self-host with trac, cgit, mailman, ...etc? Yes, of course. Just like how some projects self-host today with gitea/gitlab/...etc.

did a GitHub write this?

There are public archives. See Zenodo. Not sure what the author is complaining about.

Activitypub (the fediverse protocol) integration in open forges has the potential to provide most of the interoperability of a centralised system in a distributed environment