That was exactly my point. OP claimed that it seemed like people on HN weren't using it based on the comments to this thread so far.
I'm claiming the opposite, that a majority of HN users are also relatively happy Facebook users, but that those users won't comment on threads like this. Because these threads always attracts the contrarians and turn into a pissing contest about who deleted their FB account first.
It's hard to manage, but with the right controls and tweaks, they could make it more comfortable again... and I'd start using it again.
Kind of a good counter-example: LinkedIn may be much smaller and less loved, but when you post something there, you know it's going out to your work colleagues, and it'll maintain the respective level of discourse. FB is just all over the map.
Now, if you think Facebook provides with you with something of value, good for you. You're using a service and you're happy about it. But that says nothing about the preferences of others.