Well, that's not possible for everybody. As much as we'd all like to completely detach from the outside world while on the camino, some of us can't. I'm leaving my 10-year old child for a month, would that be fair for her not to be able to reach me? I don't think so, and it's hard enough leaving her for so long, and hard to justify that it's not a selfish thing to do. Also, for those that run a business, sometimes they have to be reached, and that is just reality, even if it means just checking once a day.
For some people leaving the phone at home is the best thing ever, and that's great! For others, it's just not possible or practical for various reasons, and I've found some people on here to be judgmental of those that have to stay connected, almost implying that it's not a 'true' pilgrimage if you have contact with home... just saying. (not saying you are judgmental, just a general comment based on what I've read on various threads).