jdporter kindly messaged me with some further and exciting historical information missing from my original post. I had totally missed an important player from the early days, namely kurt, Perl Monks user since Jan 11 2000, aka Dr. Kurt DeMaagd, PhD, formerly Assistant Professor at Michigan State University, currently working once again with nate at Sight Machine and currently a director of the Perl Foundation.

Kurt was Business Manager for BSI from Jan 1999 to Jan 2001, studied Computer Science at Hope College 1996–1999, and was a co-founder with nate of slashdot, Everything2, and Perl Monks.

For a time, kurt ran his own site "ThePope.org" which was probably running a version of the Everything Engine. Curiously, the disclaimer page at "ThePope.org" (scraped from the wayback machine) confirmed the BSI link:

BlockStackers Intergalactic LLC is in no way associated with the Catholic Church.

In 2012, Kurt co-authored with nate an O'Reilly book on Computer Vision. Curiously, the source code behind the book is written, not in Perl, but Python!

Finally, kurt performed valuable work at YAS, as indicated by these posts:

• Pledge drive update from YAS by blssu
• Membership pledge drive II by blssu
• Changing of the guard at YAS by Elian

Dec 2023 update: jdporter unearthed some more information about two more early Perl Monks Everything Engine developers: both from UMich, and both set up early instances of the Everything Engine:

• clampe 4 XP, no write-ups. Cliff Lampe. Wayback machine link 1. Wayback machine link 2. clampe also has an everything2 account clampe.
• dstb 16 XP, no write-ups. D Scott TenBrink. No everything2 account for dstb though.