digital vs physical
The problem with the Library of Alexandria and similar collections was that they collected what was in many cases the only copy of a document, so this was lost when there was a fire or an invasion. (The advantage of clay tablets was that they were improved by fire!)
With digital documents there are many versions, so they should be more durable. Unless (1) the original website owner set permissions that were unfriendly to web crawlers (I've made that mistake) or (2) the entire Web gets commandeered by some Billionnaire, who reduces it to a single copy.