She won't be able to do anything social without a smart phone. Children communicate with messaging apps etc - they don't text or call. She'll be so left out of things if her friends all have them, both actively, with people wondering why she doesn't have one, and passively, by just being forgotten about when plans are made
All the useful apps are on smart phones, not just social media, but things like maps, train time tables, google, homework apps, planners, educational apps
She'll need to take photos of things, even homework, school stuff, reminders/notices, timetables.
She'll want reminders apps and alarms and things like that
So many uses for them. Just get some good parental controls, and teach her how to use things wisely, and look at her phone now and then