Who says Fitbit is only for mobile? If you have the Connect app you can manage your trackers right from your Mac!
Sure, phones are great because you always have them with you. There's something about sitting in front of a big screen, though, with a big keyboard, and setting everything up just so. It's probably not what you want to do all the time, but it might just be useful to have once and a while.
Especially when it involves tweaking settings, friends, and other grunt work.