The Windows store charges 15%/30%, Xbox in-game purchases are a 30% cut for digital games. PlayStation in-game purchases are a 30% cut for digital games. Google Play IAP is a 30% cut. Same with Nintendo digital games. Same with Steam.
Surely they all can’t have monopoly power? Is 15% of revenue suddenly not monopoly power? Would you still feel forced to pay it if it was 50% or 75% or would you just leave iOS?