> the website UX has become steadily worse

Not disagreeing, but the Amazon web UX has been famously terrible since like 1998. They basically invented the whole trend of building via A/B test result instead of via user-centric design. Nothing on the site has ever made any sense. Every item title is a paragraph description. The categories are basically useless. The filters are a mess of bad and incomplete data to the point of being useless. Many items have 2-3 duplicate listings that somehow have different shipping dates and descriptions, and you never know if you have found the "real" listing. But they sure sell a lot of stuff.

I've always assumed the issues you described were meant to disarm users but also maybe to set expectations. When you see 3 similar items, you don't know if you're getting the "real thing". So you spend that money and expect the worst. Terrible listings make it hard to find what you need exactly but also make it seem like they have more selection when they might not.

Regardless I've considered it to be intentional.