"To people that already know some Python and want to write a web app, yes, but I don't think I ever saw a "Starting out learning Python? Then use virtualenv" advice."
People tackling Django and Heroku are not Python beginners. They have to at least know the basics first...
Even pip is not something for a first-time Python use to use. Before he gets to use third-party modules he has to learn the basics of the language, syntax etc. Have you seen any introductory Python book (Learning Python, etc) starting with the installation of third party stuff via Pip?