“To appreciate why, remember that a large share (60% or so) of revenue on the App Store is from games, and game developers are in the business of incentivizing users to take small incremental actions within a play session.”
Apple’s settlement lets developers email customers about cheaper payment options outside the app. That sounds tiny. Games already train players to take small steps for rewards, and “buy gems on our website” is one more step. The 30% cut just met the first leak that game designers know how to widen.