Or judging from comments on MacRumors and 9to5 or dozen of other Apple's focused website, Apple devices Apple rules, and this is a perfectly acceptable norm?
Yes.
Users buy the devices. They say "I allow Apple to choose what native code is allowed on this device" because of the benefits of doing so (being able to safely spend money, good UX, etc). They then are surprised when they can't run Fortnite since Epic wanted to use iOS without paying for it in the way Apple requires developers to. This is the downside of giving up that control, and it's up to consumers to make a choice on whether or not they buy an iPhone due to these pros and cons.
I see no documentation anywhere regarding this besides the Zoom forums. Thanks!