I remember when the iPhone was new, and it didn't have an App Store at all and everything 3rd party was supposed to be a web app. Lots of people were really pleased when Apple finally did what all the other phone companies were doing and let people sell directly through them.
It's a separate question if Apple has been monopolistic or abusive with the terms of that app store, a question I couldn't possible judge; but the app store in and of itself isn't the problem.
Of course there are. There are people who like the hardware, or the OS, or don't want a green bubble, but would be happy to have F-Droid or Steam on iOS, or get a discount on existing apps by buying them through someone who charges a lower fee. Or just have the competition to Apple's store which could cause Apple to charge a lower fee themselves.
As if Apple was some government provided service that you are entitled to because you pay taxes. It's not. It's a for-profit company of which you are not a board member. If you want F-droid, use Android. If you want App Store, use iPhone. If you want both at the same time, well, buy both phones then. People who want a Ferrari and a minivan don't ask Ferrari to make minivans, they buy both, because both together is ridiculous.
Your interpretation on tying is not well aligned with usual legal interpretation. Unless the App Store is considered not to be a separate product (which had been Apple's argument for a long time on App Store and Safari by designating them as "system services of iOS"), this is clearly tying. The question is if Apple's current practice is illegal tying or not. Whether the customer wants it or not is not important here; you can give them freely to gain market dominance then reap profits later on whenever the competitors are all gone.
On that note, how is Microsoft getting away with it with respect to the office apps which use to be available independently but now can only be purchased in bundles; adding Teams on top of that?
But tying (e.g. of an app store to a platform) is classic monopoly abuse.