Mstsc doesn't allow it because the login screen for windows doesn't have copy-paste. It's not that it has been disabled, it's that it was never programmed to ha

Mstsc doesn't allow it because the login screen for windows doesn't have copy-paste. It's not that it has been disabled, it's that it was never programmed to have something in the clipboard before logging in. Still, they probably could load the thing first easily, but it's Microsoft we're talking about.