Hi, I would be interested in that too. I think I'm witnessing some kind of an archival phenomena recently, everyone seems to be interested in collecting and preserving things, maybe it was always like that, not sure. Maybe it's natural... Have you found anything interesting yourself? Did you look into archive.org?
I think the desire to collect and collect rarities has always been there. But the value of virtual things such as old maps and prefabs, or even games come with time, when you understand what contribution it made to the mass culture. It would be a shame if the creations of the people who put their efforts, time and soul into them would simply disappear. I think creativity should not disappear without a trace, it carries some value
Unfortunately I did not find anything on the site Archive.org. Now in general it is difficult to find something, many links are dead. But luckily I found ftp with a copy of some archives from popular modding sites:https://www.gamers.org/pub/idgames2/planetquake/planethalflife/prefablab/https://www.gamers.org/pub/idgames2/planetquake/planethalflife/prefabland/packs/
I think there may still be something on the web somewhere from those collections of prefabs in the archives under strange names on pages not indexed by search engines. Even on this site many years ago were interested in prefabs, I think someone must have kept something