The whole point is moot, even though I agree with your take.
There were plenty of confirmation from other users in this thread having their out of the most recent iOS version iPhones (someone mentioned their iPhone 5 currently running iOS12, with the most recent one being iOS17) working just fine with iMessage.
There were plenty of confirmation from other users in this thread having their out of the most recent iOS version iPhones (someone mentioned their iPhone 5 currently running iOS12, with the most recent one being iOS17) working just fine with iMessage.