If it weren't for Amazon's dominance, other sites would be able to compete without resorting to these dark patterns, so this is a self-perpetuating cycle: people only shop on Amazon -> the only other sites that can survive are the ones that engage in deception -> trust in non-Amazon shopping sites decreases -> people only shop on Amazon -> ...
I don't mean to cast these scammy shopping websites as victims. My concern is more about how the legitimate sites that could exist don't because they're crowded out by Amazon (and other big players like Walmart) and the scammy shopping sites this article discusses.