Thanks for the feedback. We wanted to make it harder for people to add topics and industries only to get certain jobs. We will look into ways for user who don't want to connect their profile to social networking sites.
Just thinking of my own case, you won't get much of use from Facebook (I post pictures of kittens and cookie recipes), twitter (It's been nearly a year since I've tweeted anything) or Linkedin (I barely use it). You'd get more of use from HN, reddit or (especially) github, but it might be harder to extract useful information from those sources.
You could still provide buyers with awesome cookie recipes!