But autofill doesn't work on non-Safari browsers on your Mac. Yet I truly love Keychain so much in my Apple ecosystem I go to the trouble of exporting my passwords every few weeks to Chrome.
I'd like to see websites make it easier on people who need to copy/paste their login information because they are using some kind of password management system that doesn't support autofill.
One simple change would be to for the site to pick some character that is not legal in user names for that site and make it so that if the login form is submitted with a blank user name but the string in the password field is of the form <string1><X><string2> where <X> is that not-allowed-in-user-name character, then the site tries to do the login with <string1> as the user name and <string2> as the password.
People using copy/paste could then store their user name and password together in that format in the password manager, and only have to to one copy/paste to login.