I suppose anyone could create a backup using wget (see
https://en.wikipedia.org/wiki/Wget) - at least of all publicly visible threads; I'm not sure if there's more, apart from obviously private direct messages, or how large a part of the whole those deeper sections might be. I don't want to post something directly working, for fear of too many people putting too large a load on the server, but such example commands are just a search away.
Someone who does this might consider using the -w parameter to add a time delay between requests (examples: https://stackoverflow.com/questions/357 ... ts-in-wget).
I'd compile the archive myself, though somehow it seems better for that kind of thing to come from someone not so no-name - from someone who is actually recognisable as a member of the community. That, and I'm unsure about the copyright problems one might technically get into if sharing so many contributions from others.
(As a side-note, I once used wget to "save" the remains of a dying forum (for the overhyped game StarForge), starting the process just too late to get much before it was shut down. That was only for silly sentimental reasons - the Limit Theory forum seems vastly more valuable and informative. For me, this feels almost like the beginnings of a pattern; I'm wondering if I'll take a liking to a third and yet more interesting forum-potentially-at-risk...)