Getting into the bloggin habit is like getting into the networking habit. At first you're unsure of what you're doing and if anyone even notices or cared that you bothered to show up. Then you realize that you're getting some nice feedback and things are starting to happen. Finally, you see that it's a regular part of what you do and that it's vital to the growth of your business.
I'm still on the first part for blogging, and I see a lot of people who are still there for their networking abilities. From an organization's perspective, I think the most important thing is to make sure that your events are very, very approachable. When people are unsure of themselves in a networking setting, it doesn't take much for them to be convinced that the whole thing was a bad idea.
Early on in my job with the Chamber, we held a mixer where I was at the check-in, quite a way from the event itself. I was greeting members and making sure they felt welcome, but I wasn't keeping an eye on the group. About halfway into the event, a group of three people who had arrived together came back to me at the check-in, announced that there was "nothing but cliques in the room" and that they were leaving.
Since I didn't see the event (I now make sure that I'm right in the middle of it), I can't say for sure what was going on, but I can make a guess that there were two factors at work. First, there probably was some clustering going on, but there's usually still plenty of mixing going on. Second, the group of three were a little bit intimidated and weren't willing to break into any conversations or approach anyone by themselves. Because there were three of them, they probably formed their own small group which precluded individuals from breaking into their group.
I've learned since then that you can't assume that people know how friendly your group is. If they're uncertain, you really have to show them by introducing new people around until they feel more comfortable.