I live in Barcelona and phones are being pickpocketed every day here. Not being able to wipe or unlock or else is a mayor deterrent for the pickpockets, because noone will take the phone off of them, so it's not worth it. Phones are still being stolen but imagine if they could sell to a global market of repair shops.
You couldn't go to any tourist location without having your phone stolen if it wasn't bolted to your person.
I get the iFixit point as well but if I have a 1500€ phone, I don't want to think about it being stolen, when I am on vacation, because someone needs some parts (oh the human trafficing/organ harvesting similarity...)
Apple should offer a better repair program and offer the ability to "unlock and relock" it in a apple store with proper proof of ownership. Or anything else in that direction.