I'm not familiar with r/datahoarder, but if the name bears any significance, it seems they are mostly centered on hoarding data, which means just digital I guess? If so, I much rather would want to promote efforts like Internet Archive that back up all kind of things, not just digital data.
A ton of 35mm and 16mm film reels, vinyl, and even wax recording, physical books and a lot more. They make digital copies of them, but they also archive the physical versions as well. Here's a selection of the movies: https://archive.org/details/moviesandfilms?tab=about
