Earlier quoted context omitted.
Don't forget the classic "Oh, that 3rd party app/feature is so popular, I bet we could build a identical/slightly less useful thing ourselves so people don't have to use other things than Apple software ever"
Conveniently, Apple's App Store Review Guidelines also include several rules that restrict apps from duplicating features that the OS already provides. So if they detect a trend early enough, they implement it as first-party feature, dry out the existing competitors while restricting new competitors to enter based on the App Store Review...
"Apps that copy basic iPhone or iPad functionality (including but not limited to its UI, gestures, core features) will be rejected unless the app provides a clearly different purpose or adds unique functionality."
Note the "basic" line. And there are plenty of Photos, Notes, Streaming etc apps so not seeing where this is being used to exclude competitors.