I did this until last year when I broke down and got a phone because I wanted to get into mobile development. It was worth it (financially), but the freedom she talks about in not owning a cell phone is real - and I miss it.
A lot of people seem to think that turning your phone off while you take a hike is as the same degree of freedom as never having any of your extracurricular activities interrupted - ever. It's not.
Are there downsides to not owning a phone? Of course. I was just commenting that habitually being incommunicado is, for me, a peaceful state to find oneself.
Possessing a phone seems to give people the addiction of reaffirming their social value with little "New Text Message" nuggets throughout the day. Or the need to cater to every correspondence whim by immediately returning calls and texts.
I think the loss of freedom is less contingent on getting a phone, and more indicative of the general social insecurities most of us share.
It's why you shouldn't feel compelled to instantly respond to the texts of that girl you started talking to. Instead, waiting longer between conversational responses portrays more dominance, control, and "I have other shit going on in my day".