Also streaming requires reliable high-speed internet. This is easy to take for granted when you live in a major metro area, but for more rural users, high speed internet may not be available at all.
Also, while this may not be usually a problem with Netflix, in general streaming also requires enough servers on the other end, and uncongested pipe between them and you. I think most of us experienced the cases where, despite being on a reliable high-speed Internet connection, the movie still keeps pausing every minute or three, because it's not streaming fast enough to keep up with wall clock.