It's hard for me to imagine wanting to use a phone for anything other than making calls or sending SMS; that's what I've been doing for many years now and I see no reason to change. But if I did have a tablet or laptop, I could just sync the program to it and run it locally. Maybe using, for example, good old rsync.
And I can't imagine being away from "home base" on a laptop for long enough (or using it for anything critical enough) to really worry about how to achieve "centralized backups". I'd rather not transmit that data over the Internet when I could just connect the laptop physically to my backup storage when I got home.