I didn't realize that Peacock was missing. I must have side loaded it when it came out. The only real distinction between doing that and having native support is that in order to watch something on Peacock, I need to open the Peacock app. I can't search Fire and have it find results from Peacock along with other relevant hits. But didn't HBO MAX do the same thing even with the supported app? I don't keep up. If they still don't allow true integration, it means less use of their service because if I do a general search, I won't find out that HBO has it.
Allowing Amazon to integrate things is to the benefit of the other companies, and the benefit of their own customers, not to the benefit of Amazon so much. Allowing Roku to support an app means giving Roku users access. At least with Fire, I can get access to anything that runs on Android. And there's a community out there that will do the work for me, so I can find it, click it, and install it.