People who-have-heard-of-but-are-not-really-into LessWrong, in my conversations with them, have dismissed the site as an echo-chamber of inside references.

In my experience, this is one of the most common patterns of dismissal out there. It's also one of the easiest to dismiss: every intellectual movement will contain communications among insiders, and those communications will use terms that outsiders won't be familiar with.

"Wow, you mean people write for their audience? What a surprise!"

Or: "Every field has inside references." And then list examples from whichever mathematical or scientific field you're most familiar with.

Now, whether or not this is a desirable pattern to fall into is another issue entirely.