Thinking back, I only started searching for "rationality" after I'd already come across LW and was trying to figure out how I felt about hanging around with people who showed such an intense focus on that word.
It's non-obvious, to say it mildly, that the type of person who would be an asset here are people who go around Googling "rationality" in the first place.
Being the first hit for "religion evidence" or "nutrition evidence" or similar searches could well be a more desirable optimization.
I've just noticed when searching for "rationality" with Google, HP:MoR is the second hit. Wikipedia is top, which is both good and expected - but I was suprised to see HP:MoR so high up.
I think it's a good thing, anyone looking for info about rationality seems likly to be suprised by Harry Potter being mentioend, and then have a look at it.
The first mention of Less Wrong is on the second page of results, but I wouldn't expect "Less Wrong" to be as attention grabbing as "Harry Potter" when you've just searched for "rationality"