What are your concerns about Apple's app distribution exclusivity?

I’m a design postgraduate student writing a paper about Apple’s exclusive control over app distribution for iOS devices and it’s effects for app development projects (from the designer and developer perspective, and also business standpoint).

I've done a previous research and identified the following main topics:

  - Monopoly arguments (by developers)
  - Antitrust Lawsuits (in the U.S. and Europe)
  - Abusive or Problematic App Store review process (and rejections)
  - In-App purchase policy (and it's controversies)
  - "Sherlocking" (by Apple)
  - User Safety & Privacy allegations (to justify Apple's walled garden)
  - "If you want third party stores, don't buy an iPhone. You can always choose Android..." premisse

Could you list your concerns or share your experience with the App Store ecosystem that can enrich the topics I can cover?

Thanks in advance!