A few years back Cory Doctorow proposed the theory of "enshittification" to describe how Amazon had become significantly worse:

In Bezos's original plan, the company called "Amazon" was called "Relentless," due to its ambition to be "Earth's most customer-centric company." Today, Amazon is an enshittified endless scroll of paid results, where winning depends on ad budgets, not quality. . . .

Search Amazon for "cat beds" and the entire first screen is ads. One of them is an ad for a dog carrier, which Amazon itself manufactures and sells, competing with the other sellers who bought that placement.

Scroll down one screen and you get some "organic" results - that is, results that represent Amazon's best guess at the best products for your query. Scroll once more and yup, another entire screen of ads, these ones labeled "Highly rated." One more scroll, and another screenful of ads, one for a dog product.

Keep scrolling, you'll keep seeing ads, including ads you've already scrolled past. "On these first five screens, more than 50 percent of the space was dedicated to ads and Amazon touting its own products." . . .

How did we get here?

The answer, Doctorow proposed, was that Amazon had built a $31 billion ad business inside its own retail platform. The incentives for Amazon went from "give customers the most helpful results so they'll buy the most stuff" to "sell as many ads against products as customers will tolerate so that:

[ad sales profits] > [retail sales losses from abandoned searches]