The latter case falls under “inhibiting” because they not only aren’t allowed to collect payments in-app (a significant UX issue in itself) but, pending a policy change by Apple, they aren’t even allowed to instruct users how to make a purchase outside the app. Their options are to lose prospective subscribers due to signup friction or pay up to 30% of their revenue to Apple, against whom they directly compete, which many services like this can’t afford without raising prices. Apple is able to either deliver services cheaper or make more profit on services because they don’t have to worry about paying a significant chunk of their revenue to someone else.
There exist numerous examples of Apple copying nascent App Store apps’ ideas to build them into their own OSes, but the most recent that comes to my mind is the FlickType swipe-typing keyboard for Apple Watch, which Apple repeatedly stonewalled in App Review for a multitude of farcical reasons recently before building a swipe-typing keyboard into watchOS for the Apple Watch Series 7, which Apple used as a selling point for its larger display. As for acquiring competition, Apple’s not the worst offender there; that’s more of a Facebook problem.