It would seem easy to produce a Lightning adapter that you could plug any ordinary phones into. The phones that have a built in dedicated interface will find few uses. Well, yeah, you'd think Apple woulda, coulda thought of that.
Oh, they did and are including it FREE with every iPhone 7. Whaddaya know?
Yeah, 1984 Apple-World's PROPRIETARY mini jack adaptor is "free", until it breaks, gets lost, stolen, etc.... Then that nice little proprietary 1984 Apple-World mini jack adaptor is going to cost you a small fortune to replace = Another, aditional, never-ending money stream for Apple's "Big Brother".
1984 Apple-Word is ULTIMATELY all about: C O N T R O L over their Prole users.