It really doesn't have an impact yet within a forum, it's more of a wider social network feature. We have following on chainBB and that really doesn't do much to the forums either.

Right now the "Feed" section works just like Steemit (same APIs) and it's a pretty weak feature. Reworking that is an idea I've got, but it's pretty low on the list of priorities at the moment (since it's not really forum related).