Ask HN: Contact info in profiles

There have been plenty of instances where I wanted to contact a reader after reading his/her comment on HN. But there are an incredible number of user profiles that have no contact info whatsoever.

I can understand if this was digg, but on a strong community site like HN, I was surprised to see this.

Is there a particular reason why many people don't have any contact info listed in their profile pages? If not, maybe now would be a good time to update with a simple email address perhaps?