I mean, at a minimum, their habit of using customer data from their platform businesses to inform development of their own competing products is pretty sketchy.
Even if that's true, which I'm not persuaded of, Amazon's enormous market power makes a big difference. As a consumer, I don't want Amazon to "optimize revenue streams" when that reduces the reward to market participants to be innovative and deliver high quality.
You left something out, "as long as it doesn't effect me (yet), and large companies do it, it must be morally acceptable." I don't know why we defend them. Without Google we still go on. Without us, or support for their practices, they dramatically change or they disappear.
Why did your comment single out Amazon and not the practice of 'immorally' tracking customers?