I don’t use call blocking apparatus. With awareness that calller display is so easily faked, I personally regard call blockers as just another scam.
Nevertheless, people do use them and place trust in them, and providers may even offer them as a network service. By displaying a number that is randomized for every call, the phone scams might have more confidence of getting past the call blocker scams?
Moreover just displaying a number, even a number that is gibberish, will overcome the perceived security that is provided by appuratus that blocks calls with ‘number withheld’.