Oddly, I find the ebay homepage more useful, since it also displays a selection of products from sellers I watch, and has figured out I have a fetish for vintage test equipment. I don't think I've ever bought anything from the Amazon homepage, but I bought at least 3 items that I saw on the eBay homepage (from sellers I watched) in the last year. This relies on active participation from the user, however, and benefits people who have used the site for a long time. And I can't kid myself, eBay can't grow selling used test equipment and motorcycle parts, but they still do the online sale of unique items better than anyone else.
I do miss the 'rummage sale' aspect though, it's now nearly impossible to browse and find weird items, you have to just search for specific items rather than browse.
My suspicion is that they have teams of "professional shoppers" seeding the AI algorithms.
That's like ten lines of code, done. It won't be any less useful than what they are doing now
Now I choose AliExpress when I want it cheaper and Amazon when I want it faster. eBay has lost a lot of marketshare in this space - yes, there's business in auctioning collectibles and second hand stuff, but it's much smaller than that direct purchase market and they'd likely have to scale back the site in some respects.