One reason I use an Apple device is that I like knowing every app I use has been reviewed by them

That doesn't require Apple to lock down the platform. All it requires is for them to offer a store of Apple reviewed apps. You can choose those apps, other people can choose apps from other stores.

You're basically saying you like Blockbuster video because there's no porn and they only have the "edited for the Airlines" versions of movies.

Great, but other people would like to use their device for whatever they want.

Yes, I know you'll say "so buy a device from someone else". I don't agree with that anymore than I think Ford should be able to make a car you're not allowed to drive anywhere Ford says your not. If Ford did that I don't think the answer should be, "if you want to drive other places buy a car from someone else". IMO the answer should be it's illegal for Ford to control my car to that level.

I'm hoping Apple loses the case against their monopoly on the App store (although given the details of the case I don't think this particular case will succeed so I'll have to wait for another)

That's a complete non-sequitur. The complaint was that the owner of the device doesn't have the choice to install software that wasn't approved by Apple. The fact that you only want to install software approved by Apple is completely irrelevant to the question of whether you should be able to install whatever you want, because your ability to install whatever you want does not in any way affect your ability to only install software approved by Apple.

You only buying Nike shoes does not require that all other companies are banned from selling shoes, you only eating McDonald's burgers does not require all other restaurants to be closed, and you only buying software through Apple does not require that there is no other ways to install software either, that's just authoritarian bullshit.

Not really, no. You can distribute IPAs to users for them to sign locally, which Apple can't really control, but this is much more difficult.

Yes and no, see other replies for nuance. Apple controls software distribution for their platform, in exactly the same way (in principle) that games console manufacturers have done so for many decades. They do so in the same way Atari controlled software distribution for the 2600 in 1977 and Nintendo controls it for the Switch today, or that Volvo does for software performance packs for their vehicles. All these and many, many, many more are closed platform devices you buy, with optional software features you can purchase from the vendor.

Yes, all your users would have to be signed up for Apple's Developer Program ($99/year) or have a jailbroken device.

Does it matter?

It's their platform, they can choose the rules behind app distribution. They chose to allow it through methods controlled by themselves. If a third party wants to distribute apps, then they have to abide by the terms set by Apple.