This doesn't really cut their profits in any way outside of app store sales I suppose. They are still selling hardware. Adding new soures of apps doesn't, in any way, take away their "magic". That's not being taken away at all.
Also iOS and MacOS are not the same. You don't have to go through apple store to get apps running on macOS. There is no hard restriction on what software you can run on it.
Brewed coffee has more caffeine than an espresso?
Never thought of this. Thought they were relatively the same concentration.