If you look at tweens who grew up having iphones most of their conscious lives, a huge chunk of their social interaction happens online. Not in the real world.
Only the old people take pictures for family and friends. The party doesn't happen unless there's pictures on instagram proving how cool it is while the party is happening.
If one thinks it's a waste of time to take a couple of selfies instead of enjoying life, think of the time before photography where you had to pose for a painter for a week.
That doesn't make those who don't take that approach any less valid. There are still plenty of young people who don't participate in that fashion. Their photos are still just as relevant despite the fact that they are shared with a more limited audience.