Not that much smaller right-before GitHub and right-after it became available.
> but in the number of projects most of us could realistically depend on.
Most FOSS I realistically depend on I don't obtain from GitHub actually.
> There were well-known projects, maintained over long periods of time by a comparatively small number of people.
There were even more not-well-known projects, maintained for less time, by a larger number of people. They just weren't that many of them in one place.
> You knew the names.
You absolutely did not know the names. Post author is just thinking of the names they knew as though those were everybody.
> reputation mattered in a very direct way.
And now it doesn't?
> We took pride (and got frustrated) when the Debian folks came and told us our licensing stuff was murky or the copyright headers were not up to snuff, because they packaged things up.
RedHat was just as popular a distribution; and most users used Windows (like they do today); and the BSD distributions were a thing (although we didn't have Apple's BSD, i.e. MacOS)
Bottom line: Inaccurate description of history.