Not weird at all. I do have referral signups who write Hubs, but only two out of a hundred are writing large numbers of Hubs.
There are lots of reasons why that happens. Sometimes people sign up just to comment or participate in the forums, and have no intention of writing Hubs at all. Sometimes people sign up, then look around the site, find it too hard and don't get started. Or just don't get around to it.
I used to try emailing my referral signups to welcome them to HubPages and offer my help to write their first Hub. it worked so rarely, I don't bother now.