A better question might be "could you live completely off grid"
or "how self-sufficient could you be if you had to".
I think most of us long time off grid homesteaders will honestly admit we still go to a store on occasion and obviously we have computers and internet. But you will also find that we provide our own power and have our homes designed so if we couldn't get to a store for a long time we won't suffer any great hardship. And having internet is not much different than listening to the radio these days. I use free wifi at the public library for my internet because I have to go in town almost every day to care for my elderly mother. It works for me but if I needed it for work I would get a sattelite hook- up. Part of being a homesteader is living independenty and self- sufficiently and for many homesteaders the internet allows us to work from home so we can do just that.
There are some "true" survivalist homesteaders that live completely self-sufficiently or so I have heard. But you won't find them on the internet. And that isnt a lifestyle I want for myself.
LaMar (who is a true off grid homesteader)
http://www.freewebs.com/simplesolarhomesteading