Okay great, seeing how every reasonable warning and technical restriction is completely pointless and how people will do everything they're told if they're naive enough and the person on the other end is convincing enough, we can skip this whole dance.

Because at the end of the day the scammer is going to convince your grandma to go to the bank, withdraw the entirety of her savings and send them to the scammer in an envelope.

Any technical restrictions therefore only harm our personal freedoms and don't actually protect those who are vulnerable because those people's problems aren't technical in nature.