I think the point is that younger people tend to be early adopters of a new platform. It's probably easier to get middle aged people to start using a platform p

I think the point is that younger people tend to be early adopters of a new platform. It's probably easier to get middle aged people to start using a platform popular with 20somethings than the other way around. So if one wanted to create something to rival facebook, create a place that suits the needs of the younger generation better than facebook does, the rest will eventually follow. Even reddit seems to have a healthy following amongst "older" people.