Back in 2001 advertising was far more lucrative than it was today. So a website could be both: useful, and a for-profit, ad-supported enterprise. Hell, the reason why most online versions of newspapers were free was because advertising was so lucrative. Now, ads pay peanuts, and only make sense if you already have ludicrous scale, or are able to game search results with low-effort """content""" to get that scale.[0]

So it's both "less signal" (fewer high-quality websites) and "more noise" (more spammy SEO-to-oblivion sites).

[0] A similar thing happened to video advertising, which is why even really good YouTube videos are filled to the brim with ad integrations, merch tie-ins, and calls to like and subscribe.