...but seriously... I think I still remember my "license plate" number for prodigy.net, which I think was 7 digits alpahnumeric. I've very occasionally searched for it thinking there was maybe an archive or footprints from "those days" but nothing has ever come up.

Quite literally the transition of physical paper => digital forums => internet (pre-crawlers/pre-archive) => where the data could have been lost before it had a chance to be "modernized".