It shows community involvement

Involvement in a mostly social forum where the vast majority of technical discussion is answering Faqs to people who can't RTFM isn't the best thing on your resume. Think of it this way, if someone applied for a job and said they had 1200 posts on Slashdot, would you be more likely to give them a job? It can be a liability. Actual involvement in open source projects is exponentially better, and you'll learn more to.