>>Wouldn't you agree that the world would be a better place if we had less of them?
There would first need to be consensus as to what constitutes an artificial monopoly. So far the term has been used so nebulously as to encompass any choice or decision made with a tradeoff or constraint that somehow paid off for at least one but few, if any, others. In other words, "They cheated by holding onto a winning strategy / lottery ticket."
>>General computing devices like a phone (unlike gaming consoles and media like your examples).
I fail to see the distinction. The Nintendo Switch is powered by the same SoC that runs on the Android-powered Nvidia Shield. Just recently, the Switch has been jailbroken to run full Android 10. The PS4, PS5, XB1, XBSX all run on x86-64 AMD chips (the former two on an in-house OpenBSD distro and the latter two on a full Windows 10 kernel). Even older consoles like the PS2 and N64 can run Linux (the former as an official feature and the latter as a recent homebrew development). In short, anything in console space has been a general computer for the last 20 years if not earlier. Constraints are imposed onto the hardware and software of these products as a natural consequence of certain physical limitations or by intentional design of their respective companies. Apple's products are, in general, no different.
>> We already know Apple doesn't need the App Store for iDevices to be a commercial success.
What Apple needs to be a commercial success or not is a choice for Apple to make for itself. Apple chose a particular domain to succeed in and succeeded beyond almost every expectation. Absent fraud, it shouldn't be stopped from monetizing it's winnings any way it chooses just because you think the company has "over-succeeded". That on it's own doesn't make the App Store an "artificial monopoly" any more than it makes Usain Bolt "too good" to be allowed to compete in any more races. All of which leads me to question how exactly you are defining "artificial monopoly". What counts and what doesn't?