Not enough high-status people, especially scientists and philosophers. Do Richard Dawkins and Daniel Dennett know about LW? If not, why not?

Well, to be blunt, arguing on public internet forums is not an effective way to accomplish anything much in practice. The only people who do it are those for whom the opportunity cost in time is low (and are thus necessarily underachievers) and those who find it enjoying enough to be worth the cost (but this is clearly negatively correlated with achievement and high status).

Also, arguing on the internet under one's real identity is a bad idea for anyone who isn't in one of these four categories: (1) those who already have absolute financial security and don't care what others will think of them, (2) those who instinctively converge towards respectable high-status opinions on all subjects, (3) those who can reliably exercise constant caution and iron self-discipline and censor themselves before writing anything unseemly, and (4) those who absolutely lack interest in any controversial topics whatsoever.