I don' believe Amazon does do that to people who buy unregistered Kindles.
In fact, IIRC it is pretty easy to just refuse to connect to a WiFi network and fail on trying to register, then go straight to regular old unregistered-but-perfectly-usable mode.
No clue why your wonky PW3 isn't offering that, but, well, it seems to have several problems. I'm not sure it is fair to judge newly-purchased PW3s based on that.