Which can't possibly be actually true, since advertiser bids must necessarily be funded by actual product sales - I guess there's an edge case where an independently successful business intentionally overspends on Amazon ads to quash potential competitor discovery, relying on non-Amazon sales to make up for the deficit, but I can't imagine that's a particularly common result.

If people give up on buying things from Amazon because there's just no way to find reliably usable products, Amazon will eventually lose out on that advertising revenue. So either we're mid way through that process, or there's something more complicated going on.