GarageBand. iMovie. Both of which can have their projects opened in Logic Pro or Final Cut, an irreplaceable workflow for which there is no Android equivalent. Audio Bus. Not Google. For me, ARkit is huge for some hobby projects.
I don't understand why this is such a big deal for them. They could even charge more for it, or make it so tech support is excluded from those phones, or whatever they need to do make money.
They'd bring all the hackers back to their platform. Do you realize how much effort is spent on Android mods? Can you imagine if those people were busy making iPhones do more thing? Because that's what'd happen if they'd sell me a rooted phone.
Not having root has never affected my almost ten year iOS dev career.