Exactly, I'm a developer (mobile apps and games hopefully - if I can ever actually finish it) and I get why I might want multiple options but as a consumer? The REASON I choice Apple is the superior App Store. No where else can I find the average quality of software that is on the App Store, the freedom form viruses, and general quality of app.

The App Store will not stop existing if sideloading is made possible

Because I'm not limited by what the store decides they want to sell me. For example, there's no PornHub application on the Apple App Store. Similarly, Apple has been under fire recently for blocking streaming games, such as Microsoft's Xbox Cloud Streaming or Google Stadia even though it's functionally not different than Netflix's movie streaming, just with input. Or even blocking Steam's remote control Steam Link app from accessing the store: https://arstechnica.com/gaming/2019/05/apple-reversal-allows...

Does them blocking those help me in any way? No, it is just to protect Apple's profits because they want to take a cut. You can't even pay for Netflix through the app, because Apple want their cut.

Well, as a consumer, if I could install Kindle through a third party app store, I'd be able to buy books directly in the app rather than having to go through a dance to get to a browser to buy a book.

This is because Apple would charge Amazon 15/30% to clear the transaction while Apple Books can be both more convenient and doesn't have to give up a large chunk of change to someone else.

Choice is a good thing. Games are far cheaper on windows than any other platform because choice has forced stores to compete on fee and provide sales to entice customers.