Grocery stores and department stores have played games with what items they stock and where they stock it (location on the shelf is hugely important in a grocery store) for decades, it's just better hidden than the 'sponsored' text next to Amazon paid ads. It's infinitely easier to make a product and get it available on Amazon.com than it ever was to get your product into a grocery store.

>They know the best-reviewed, least-returned, best-priced model. The only purpose of the ads is to get you to pick an air fryer that isn’t that one

As others have pointed out, without ads, even if you make the best air fryer on the planet tomorrow, good luck getting people to realize that.