This is a fallacy and needs a name.

I always read it so it is not a fallacy, just so I dont argue.

My change: "where are the people who are against X now that the proponents of X are posting"

However it only makes sense in places like HN that have a "tone".

I think arguments in general get downvoted, or at least not upvoted, so perhaps people (other than me) are less likely to give a different opinion than the current thread.