Well, you can call me old-fashioned, but I do not spend all day and all night fiddling with my smartphone. I have a business to run.
OK, a phone is invaluable for keeping up with what is going on. I can access my email and message people if I want to. What I cannot do with is being interrupted constantly.
My work is technical. I need to concentrate. I can set aside times to look at my email whether I am out or in front of my computer. If I am with a client I cannot answer my mobile / cell, and even if I did, I could not answer a question from a client purely from memory. I would need to have their virtual or physical file in front of me. I might be able to look at a file in the Cloud, but not easily when I am out.
I do not really use my smartphone for business at all because of the way I work, so I do not even claim the cost of my contract as a business expense.
People who know me will say I am quite a techie. I am. I love gadgets, but I do not let them get in the way of my work and my business. How about you?