Not entirely sure, though I believe I did post a couple of comments to Overcoming Bias a while back. I used to comment on reddit and comment semi-regularly on Hacker News, which refutes the first explanation that I thought of, that it was a matter of my time, since clearly I do sometimes take time to comment on the internet.
The comments here are high quality, which is somewhat intimidating, and also makes things take longer, since I want to think more carefully about what I say, but that would probably apply to Hacker News as well.
A possible explanation consistent with the quotation I mentioned is that even though I read all the posts here and on Overcoming Bias, I don’t think I’ve thought about the issues deeply enough to have much original to contribute. And that may have something to do with the fact that most of my friends aren’t all that interested in the topics. I imagine if I were talking about the posts more often in real life I would feel like I had more to contribute.
I am reminded of Paul Graham’s explanation for the low number of female startup partners from Ideas for Startups:
I would suspect that all the more fundamental reasons (2, 4, 5, 6, 7, and 8) are factors, but that they are then magnified by 1 and 3. As far as 9 is concerned, I am female myself and have never commented on Less Wrong before, to provide a single, anecdotal data point.