I like Apple forcing use of in-app-payments, I like Apple giving me subscription control to make canceling easy. I like Apple blocking app tracking and forcing design constraints.
That said, the 30% weakens their entire argument about this and is a racket. If they want to charge a yearly deployment fee or something fine, but 30% of a company's income via IAP? That's obnoxious and anti-competitive, particularly in cases like Spotify where they directly compete and undercut them in the same market.
Apple is skimming a tax off the top and they're forcing everyone to pay the toll. It weakens their entire argument. I wish they would stop, because I think a world with multiple stores and such would be a huge pain and customers would suffer because of it.
If you think it's a pain to have 15 streaming services or 10 different game distributors all with their own shitty incentives - it'd be that on the phone.