Here's something to pick our collective spirits up:
According to Google's infallible algorithms, 20% of the content on LessWrong.com falls within the 'Advanced' reading level. For comparison, another well-known bastion of intelligence on the internets, Hacker News, only has 4% of it's content in that category.
Strangely, inserting a space before the name of the site in the query tends to reduce the amount of content that falls in the highest bucket, but I am told that highly trained Google engineers are interrogating the bug in a dimly lit room as we speak, and expect it to crack soon.
Nobody's making anything actively difficult to read, nor did I advocate working to increase the reading level.
However, one-shot unexpected measurements of proxies do carry useful information. In this case, this is weak objective evidence that the conversation on LW is of especially high quality compared to other esteemed communities. That is all.
If anything, it's weak evidence that the conversation is of poor quality. Doing the same search for TrueOrigin.org, a creationist site, for example, shows that it gets 70% 'advanced', 29% 'intermediate' and 0% basic.
'Advanced' reading level is almost always a pretty good proxy for obfuscation, rather than for intelligence.