SEO was/is a good thing because it made search a lot better for many years. The real problem are the individuals gaming/abusing the hell out of the system. Add AI content to the mix and I do fear it's a problem that can't be sorted out by Google Search, at least as how we know it now.

It still has its uses and I personally still turn to it (well DuckDuckGo usually) to find specific things. But like all things, it's one tool that serves a certain purpose.

I don't remember SEO ever making search better.

That was definitely a major factor in making things suck, but I don't think it (nor LLMs) were required for the rise of annoying content-farm sites.

Exactly. There's been a lot of easy to identify trash on Google for a very long time that they haven't bothered to deal with. I bet it's partly because they rely too much on metrics. "Oooo lots of people clicked on the clickbait! They must want more!"