Lack of interaction and engagement outside of BDC is a chicken and egg problem Amor. If people think they won't network outside, obviously no one will know them outside. If no one knows them, other then auto-vote and/or a follow of a curation program, there is no way to get any personal vote. If vote is all we are talking about.
This is the specific reason I like to detach people from vote, and let people focus on networking. However, this has been mostly a failure. I have seen probably 3-4 people to network outside.
I will tell the reason as well, if you get a $15 vote without any effort, why would you go outside? $15/day is a substantial money in BD, even $10/day is substantial.
So this brings forward an endemic problem that we face, only you can fix it.
There might be the case of language and cultural barrier. Many are comfortable with their tribesman and if communication grows stronger, the need to branch out might be little.