(note - that doesn't mean they can't make money. Looks like a pump-n-dump to me)
The Amazon problem could be harder to manage as they scale since they can't do subid tracking per user and probably try and correlate redirects to specific Amazon purchases, but that is going to leave a lot of grey area for any other purchases the user should be credited for but turns out to be too difficult to correlate.
When someone "games" a system to any major extent, the tracking data would expose that users "gaming" attempt.
Additionally, since you take no cut of the affiliate payment, I'm trying to find out who you're actual customer is?