Let them paste passwords
Of course it reduces security. It makes you resort to either<p>1.) typing it out manually while you can't see if you made a mistake<p>2.) using developer tools to set the 'value' attribute directly<p>"SPP" discourages use of a password manager. End of story. I also see this pattern used on banking websites for inputs like an account number. This drives me crazy as well for the same reason. The computer can get it right more reliably than my eyes and fingers.<p>Whenever I see a website that blocks paste I immediately assume it's built by incompetent people and trust it with as little as possible.