Perhaps they’d have retained value if they had been attached to quality art rather than awful-looking algorithmically generated complete trash.

No, they wouldn’t have. Because owning a link to a thing doesn’t mean anything, no matter what that thing is. They were only valuable because people didn’t understand NFTs and wanted to get rich quick.

The concept of a certificate of authenticity for digital goods that can be traded isn’t inherently terrible.

The concept isn’t, I agree. But it also isn’t a useful idea, either. There really doesn’t appear to be any benefit to using NFTs in any meaningful application, or at least nobody has pitched one that isn’t either a grift or a way to appear “trendy” by reinventing the wheel.

Some established, legitimate artists have been selling NFTs with their originals. But sure, overall, like crypto in general, the field is filled with scammers and get-rich-quick schemes.
I know someone who is a painter who for some reason decided to try selling NFTs a couple of months ago (I pointed out it was a bit late…). The only responses on opensea and Instagram she received were from scammers, trying to pull a “my payment didn’t work, you need to manually approve it” scheme to try to steal her credentials.