My point is that if Amazon e.g. directly integrated with any one of those solutions you'd enter an adversarial scenario, and all of the scammers would try (and almost definitely succeed, even if just by brute force chasing false negatives) in finding a way around it.

The same would happen if e.g. half of Amazon customers would use one of these solutions.

The difference between being online versus being in an adversarial scenario largely depends on how / to what degree you're visibly impacting the bottom line of the scammers.