I think you have the causality backwards. If someone's storing passwords in a text file on their desktop, they will probably copy/paste those passwords if the

I think you have the causality backwards. If someone's storing passwords in a text file on their desktop, they will probably copy/paste those passwords if the functionality is available. However, they're probably storing their passwords somewhere because they have trouble remembering them, which doesn't change if you block pasting. You can have a passwords.txt file and just consult it to type in your password every time. In theory that might help you remember it after being forced to type it a few dozen times, but many of the sites that block pasting also force password rotation riiight around when you finally start remembering it.