I don't fully agree with this. I like that Archive.org exists, but I don't really mind if most of the archive would come to disappear. There is a lot of garbage being generated on the web and I really don't think there is sense in saving it.
On the other side, Wikipedia is knowledge, pure knowledge, and this is worth preserving in my opinion.
I agree about the tide of garbage, but on the other hand garbage is intensely interesting to historians. Think what one could do with a decent sentiment analysis AI and billions of comments on news stories for example. By themselves many of them are just nonsensical ranting for one or other political viewpoint, but in the aggregate you could probably identify significant historical tipping points that inflected much earlier than 'official' indicators.
This comment from a long-ago article [1] about saving many Usenet postings that would otherwise have been lost applies:
That’s why not only the very earliest Usenet posts, before Spencer started archiving in 1981 (Usenet began in 1979) but even some of the posts in the 1980s are still lost. It’s too bad; today, wouldn’t more of us rather see what was being said about abortion in 1984 than sift through the arcana of bug fixes in systems that have probably been long since retired? “It was perfectly reasonable from the viewpoint of stuff that we might want to use again, but a little sad from today’s viewpoint,” Spencer admits.
It sounds like you have only ever used the WayBackMachine. Their audio collection is phenomenal. But that just scratches the surface. Tv News archive, Texts, games, and so much more.
On the other side, Wikipedia is knowledge, pure knowledge, and this is worth preserving in my opinion.