The problem is that humanity now has an incentive to produce spam content (ad money) and programs that can meticulously craft spam content to look like it’s written by a human (LLMs).

I have to assume that the result is tons of spam content, which the traditional search engines have to sift through.

If they’d present you with all that spam content, you wouldn’t find anything useful.
So, they try to filter out that spam content, but because it looks like it’s written by a human, they’re going to accidentally filter out useful content, too.

There’s also at least some measurements, that search results are decidedly getting worse: theregister.com/…/google_search_results_spam/

So, yeah, I think, all traditional search engines are massively struggling with this. Maybe something can be done with only indexing known-good sites, but for specialty information, like the repair information of your household appliance, that will probably be worse…