Apple's dominance isn't from hardware alone. But they are exceptionally talented at it. It isn't in software alone, but again, they know what they're doing. They've got a lot of mature, battle tested code and an outstanding developer community who knows how to wield it. It's not in digital distribution alone, but yet again, they got there very early, have a lot of practice and many deep relationships with the rogue states (thanks, PG) who bully would-be media companies.
Marketing isn't their top achievement, but they love the things they make and the authenticity of their marketing works very well for them.
I could go on and on, but you probably get my point.
Apple's core strength isn't any one thing first, then something else second. Their strength is their ability to see the whole board and make every single thing they do complement everything else in a very meaningful, very equal way. It's an absurd game they play, a combo of three dimensional chess and hacky sack, but their focus makes it work.
No one can compete with Apple by trying to crib any one of their strengths. To be successful, you need to be able to attack several of them at once, and that's very challenging.
They've created an absurdly defensible position. The vision needed to get there makes my brain hurt. No matter how you feel about Apple, you can't argue that their organizational synergy is an incredible force.