Activation Lock is a weird feature. Users love it when it helps prevent device theft. But really, at the end of the day, you're giving up control of the device to Apple.
Apple has already stopped supporting activation of certain versions of iOS[0]. Also, just as a user can request locking down a phone at any time, Apple could technically lock down your device when they see fit. They're not going to do that, but the fact that it's possible is a bit freaky.
Someday, far in the future, their activation servers will go down, and no unactivated Apple device will be usable. Already, it is not possible to set up a new device without an Internet connection. Hopefully the jailbreak community figures something out by then, or maybe Apple would release a tool...
Apple has stopped signing older version of iOS for devices that could upgrade to later versions. The case you linked to is an iPhone running iOS 9 when Apple will happily sign iOS 11 for that device. iOS 11 is that latest version of the software that will run on that device.
Do we blame Google for not allowing Chromebooks to stick to an older version of their OS?
This isn’t about signing the OS updates. This is about the device contacting Apple’s activation servers during initial setup.
In the linked thread, the users have a “working” device with software already installed, but the activation fails with a cryptic “Activation Error” without any reference to the fact that they must update.
Typically, Apple continues to allow activation on older OSes, as long as they were installed previously. I’ve intentionally kept some devices on older versions, and personally have never had a problem activating after a reset. But I suppose that’s only possible because Apple allowed it.
EDIT: I was wrong about the "Activation Error" not mentioning a software upgrade. It does mention it. But my point about Apple controlling access to the software still stands. It's something weird that Apple did specifically for iOS 9 and the iPhone 6s. Naturally, who really cares about one random version combination? I don't in this particular case, but the fact that Apple can control it is weird to me.
Apple has already stopped supporting activation of certain versions of iOS[0]. Also, just as a user can request locking down a phone at any time, Apple could technically lock down your device when they see fit. They're not going to do that, but the fact that it's possible is a bit freaky.
Someday, far in the future, their activation servers will go down, and no unactivated Apple device will be usable. Already, it is not possible to set up a new device without an Internet connection. Hopefully the jailbreak community figures something out by then, or maybe Apple would release a tool...
[0] https://forums.macrumors.com/threads/apple-no-longer-activat...