Firstly, as someone who is frequently driven nuts by strawman arguments, thank you for spreading the general message!

In this particularly case though, I think you're missing the point. Apple takes an opinionated "we are right" approach to design, and it's typically an all-or-nothing thing. If Apple decides to allow choice, then you get choice. If they don't, then you don't. It's one whole, beautiful, integrated system (as they would say). There's a lot of (intentional) friction[1] in place to make keeping a toe in or out very uncomfortable.

[1]: Don't think this needs a citation, but if you disagree take a look at the "buy your mom an iphone" stories and the internal emails about making iMessage work on Android (Apple/Android families and all that)