They are both reading material, but this is the story of breadth vs. depth. It’s the difference between speaking to one person for a few hours vs speaking to dozens of people in an hour.
It’s likely after having spent 6 hours on Facebook, the value of what you know or what you are capable of is unchanged.
It’s unlikely that after reading a book for 6 hours you feel as though you aren’t somehow better for it in some way.
I’m diminishing the connection to others. My parents use Facebook to see their grandchild. It’s a wonderful medium. The problem is when people start to default to it. To feel as if they are going somewhere to feed their brain information.
A book can be a wonderful thing, and a wonderful break from a screen filled world. Perhaps it’s time to up your book quota, and decrease your social media time. You may come out more clear headed, with better thought out ideas, and happier for it.