Like you say, every one of us has different interests and attention span to actually seek out knowledge that is relevant to us. People might not want to migrate from Facebook to Steemit simply because the way content is organized is just not efficient. I'm hoping to see Steemit evolve into a platform where users create and share information more organically rather than the resteeming or spamming blog posts to make money.
This is the largest hurdle I think Steemit has to rectify in the alpha version.