First of all Every thing has positive as well as negative effects,
It totally depend on how to use it,
Internet is full of negative and positive things,
Negative things includes porn etc etc,
Positive things includes knowledge about anything.
As far as social media concern it too have positive as well as negative effects.
We have started spending more time on social media, it something negative,
but if we think positive, it allowing us to have interaction with others people, their culture etc etc,
Steemit indeed ! is a great platform,
I don't know it will beat facebook or not, but i'm pretty sure it's the future.