I've just learned that SOCKS5 with authentication is still available in another less popular browser which names begins with 'Max...'
Posts made by csjjpm
RE: Can't get to hidden Opera Preferences pageOpera for Windows
the Windows 'Internet Options' don't allow for authentication with SOCKS5 which may have been the original point of the post. This is what brought me here. I've gone back to a version 12 which still has the option for username and password for SOCKS5.