I agree with this if you simply look at the site as it is, but the kind of movement that gjm is talking about has certainly happened, and Eugene's downvoting may have contributed to that.

Some years ago, if you even mentioned religion or a culturally conservative practice without saying something negative about it, you would very likely be downvoted. I'm pretty sure that even happened to gjm on at least one occasion -- he was downvoted and added, "I don't see what's wrong with this comment," and I'm pretty sure it was downvoted just because he didn't add something negative when he mentioned religion.

That is obviously not the case anymore with religion. And I just recently was giving some arguments favoring a policy of no sex before marriage, without that kind of result. Of course people still disagreed, but they didn't object to the fact that someone was arguing that point.

So it seems to me true that there has been a substantial amount of movement, even if it is still true overall that LW is more leftwing than not.