Forbidding copypaste is equivalent to forcing one to recite his address and credit card details loudly in public every time he wants to enter his own house. In an age where videosurveillance is trivial to set up, it's just stupid; there is a reason every cash machine/atm asks you to cover the number pad as you type your PIN.
If the problem is the risk posed by password vaults and clipboard managers, promote better vaults and better utilities. Personally, I'd love a password vault that could check which application or website I'm pasting to, blocking transmission if it looks wrong. But it's not the website's job to tell me how to manage my secrets.
If the problem is the risk posed by password vaults and clipboard managers, promote better vaults and better utilities. Personally, I'd love a password vault that could check which application or website I'm pasting to, blocking transmission if it looks wrong. But it's not the website's job to tell me how to manage my secrets.