Then they should clear the clipboard via JavaScript when submitting the login form, not prevent pasting of the password. Password managers are simply too much

Then they should clear the clipboard via JavaScript when submitting the login form, not prevent pasting of the password. Password managers are simply too much of a win to block. Clearing the clipboard would be annoying for people who commonly copy a bunch of text out of a document, log in to their bank, and then paste the text somewhere else, but I suspect this is a rare workflow for most people.