>"The best" is not a static product. If Amazon had no way for vendors to showcase their product ... Would you want to live in a world in which you CAN'T bump your placement?
Agreed about it not being static, but I don't see why ads should be that answer. The easiest way to "bump" a product is just sell it for less for an introduction period, so that people sorting Low->High will see it before the current highest rated one, at least until they get high ratings, and then can increase the price. If they're going to be losing money on marketing, it would be nicer if it goes to consumers.
This is a weird hack to avoid the obvious concept of "telling people your product exists".
You're also just one step away from suggesting it should be put higher up in the search results - which is the entire complaint!