Actually what I think is that we people have made our connections to people on Facebook and they are on Facebook not on steemit. I think it's because of those people we don't want to leave Facebook, but honestly I have forgotten Facebook to at least some extent.
Facebook has created a mental grip on our minds so we feel the need to use it. But trust me a time will come people will understand that Facebook has nothing to offer and they will all look out for something productive and beneficial and what better a platform than steemit.