This is because the majority of webpages are on commercial (for profit) sites now and for-profit companies do not build anything that lasts. Part of this is their use case requirements: CA TLS has to be the only way to access the sites. And since CA TLS is extremely fragile and short lived, so are the sites. But additionally, any dynamic site also has a short lifetime. HTML files-in-folders sites will last till the heat death of the universe unmaintained. A php or nodejs/etc site will last a year or two after it stops being mantained.

The core of the web pages on the internet are still there. It's just that the thick layer of commercial cr'app' websites built up on top are transient.