Why do some sites block paste on forms?

I've noticed (as I'm sure we all have) several sites which block copy and paste.

Many questions and answers on ux.SE seem to focus on a client wanting to protect their content, but I'm specifically asking about blocking paste.

Contexts I see most often:

• A credit card form which blocks paste of card details
• A signup form asking to verify a password, blocking paste
• A signup form asking to verify an email address

It would seem this is counterintuitive even by spurious "security" logic. Has anyone been asked to implement this, and if so, what was the reasoning?

Does anyone have any data?