Oculus is currently not selling the Quest 2 on Amazon, and there is no official explanation as to why. However, there are a few theories as to why this might be the case.
One theory is that Oculus wants to avoid competing with its own retailers. The Quest 2 is available for purchase on Oculus' own website, as well as through authorized retailers such as Best Buy and Gamestop. By not selling the Quest 2 on Amazon, Oculus can avoid having to sell the headset at a lower price than it would like, in order to compete with Amazon's other offerings.
Another theory is that Oculus doesn't want to support Amazon's advertisements. The Quest 2 is a popular product, and Amazon would likely want to feature it prominently on their website. However, Oculus has its own advertising campaign for the Quest 2, and may not want to support Amazon's ad campaign as well.
Finally, it's possible that Oculus is simply not ready to sell the Quest 2 on Amazon yet. The Quest 2 was only released in October 2020, and it takes time to ramp up production and get products listed on Amazon. It's possible that Oculus will eventually sell the Quest 2 on Amazon, but for now, it appears that the company is not ready to do so.