To me it appears that a modern iPhone is the most secure phone you can own. Not claiming to like it, but it is better than the one alternative OS you could use.
And other than the big players? Linux on your phone - probably a PITA; Linux on your Laptop/Workstation - fine if you don't need specific programs. But want to develop for iOS? It's mac all the way.
Because of how restrictive apple is, if this is a requirement then none of the other reasons matter
That being said, I've been living, working and playing fine over in the android and linux ecosystems. "Specific programs" like xcode I guess, but most everything else has a generic equivalent
It helps the dyed-in-the-wool apple customers have an unassailable reason for their device being better than Android / Windows.
It's a genius move, but one they didn't really have a choice but to make (which takes the genius part away) because of the timing: They're the single big tech company on the side of user privacy.
(I'm an Android user and tend to avoid Apple products because I think they're overpriced and not customisable enough for someone like me who gets bored easily)