Competitors seems to have a combination of: - Being more open-source - Have more contributors - Have a narrower scope
Maybe they should consider open sourcing all the tooling (like Xcode) otherwise the gap will only grow over time when compared to other languages.
They painted themselves in a corner. Apple being the best computing platform while trying to please everyone can never be a serious proposition. Either they are the best and everyone uses macOS, or we have to be so careful that any alternative is more interesting that what they propose.
"Best" obviously means different things to different people, but at least by market share, macOS has never been the best. Modern Apple doesn't seem to care about market share outside of the iPhone (and even then, they are still more interested in the iPhone being a premium product than winning on market share).
I used to like macOS, 15-20 years ago, but now it's just power-user-hostile and considerably more locked down and buggy. That's not the way to be "best", by any metric I can think of.
Sure, macOS has continued to secure more and more elements of the OS. They have taken a different approach than Windows and Linux, which both keep large swaths of the OS woefully insecure from third-party apps for legacy reasons. But for each and every new lock, there is a key. An incredibly secure OS that gives you the power to control what third-party apps access on your computer is the best power-user feature.
When Apple secured the OS from third party, they also purposefully closed the door on deeper third party integration to privilege their ecosystem.
macOS only being half as useful for Android users makes it harder to be the "best" for that swath of users. iPadOS being the only tablet form in the ecosystem will also distance other users etc. They just can't please everyone while locking them in a limited ecosystem.