I find it interesting to think about this while listening to historical content like the Fall of Civilizations podcast. Tl;dr, if you want something to survive for millennia, it needs to be carved in stone or you need to arrange for monks to keep transcribing it

I only started to really appreciate having a web page archive after cataloging the coffee I drank, which often have pages full of detail about the beans until they sell out and then, poof!, they’re taken offline.

I think archive.org holds onto copies of websites, even if they're no longer accusable on the wayback machine, as long as they don't get a direct deletion request.

If a domain gets parked and someone adds a robots.txt that disallows all, past versions become unavailable in most cases. Very annoying.