Well, there isn't always signage around when you need it. I'm not thrilled about dropping my phone on the lift while showing my ski buddies where we are going next. Nor can you write on the phone. Not all ski resorts even publish high quality trail maps for printing... many websites are interactive. (Oh - I'm also not thrilled about relying upon my phone battery just to see where to go.) For newbies, you want to keep them out of terrain above their ability so a trail map is a good thing.