That's exactly right! Then fewer and poorer apps would be built on iOS, and users would notice, and they would migrate to other platforms. This has happened plenty of times before. Yes, Apple has a monopoly over the iPhone - it's an Apple product. Just like Sony have a monopoly over the PS5, and Samsung has a monopoly over the WF45R6300AV Front Load Washing Machine.
The only fair resolution would be to allow Apple to do whatever it wants with Apple devices. If everyone at Apple collectively lost their minds tomorrow, they would have every right to pull all apps from the App Store completely. They could shut down the platform. It's literally theirs in every sense of the word. They built it. They own it. They operate it. Just because people are concerned doesn't make socializing iPhones or the App Store in any way reasonable.
You're admitting yourself that there's not much value provided by the appstore to developers and they only use it because they have not choice (and I do agree with that being a developer myself)
It's called market abuse. Other companies have been broken before for abuse, that won't be the first one.
The only fair resolution here is to force Apple to compete with other storefronts to prove that the value they provide is competitive. Apple could resolve this issue in a number of ways, but they've only chose to make the problem worse; that's why 34 states have come forward voicing their concern[0], and why EU regulators have been stepping in to block Apple's service expansions. They're the largest company in the world, and they deserve the most regulatory scrutiny for it; anything else is a failure of democracy and capitalism.
[0] https://finance.yahoo.com/news/1-dozens-u-states-apple-03470...