Yes, being active on Lesswrong is probably superior to most undergraduate classes in philosophy. But this isn't Lesswrong specific. Seeking knowledge on your own is almost always better than taking knowledge from a teacher.
Do you feel, for instance, that LessWrong provided you with more valuable human capital than your introductory general chemistry sequence?
No, not even a little bit. Lesswrong's strength is philosophy, and unfortunately philosophy doesn't generate much human capital unless you're in some very specific fields. Lesswrong might have sharpened my philosophy skills from 90% to 95%, but really the average scientist only needs a philosophy skill level of 70% to be effective, to say nothing of other professions. And you've got to be at least at philosophy 75% to even start reading a lot of the material here - I don't think it's accessible to, say, your average redditor.
Human capital comes primarily from knowing facts and having skills.
That said, reading primary literature on my own contributed vastly more than my coursework contributed, in terms of facts. Coursework did sometimes fill in some parts I might not have taken interest in on my own - but simply talking to other scientists would have fulfilled the same function.
Knowledge which is systematically fed to you is not customized to your interests, is not customized to your abilities, and it's not customized to your intelligence. It shouldn't be surprising that sources of knowledge you've discovered on your own are superior to those which have been given to you.
For the demographic who can learn theory on their own,, school is for degrees, making connections, and hands-on experiences - not learning theory.
By the way, there is one benefit of a systematically fed knowledge -- it prevents you from getting into selection spiral, where you want to learn about something, find the first piece of knowledge belonging to some small subset of what you want to learn, become impressed and learn the whole subset... mistakenly believing that you actually learned the whole set.
For example, one can learn programming in Java and believe that "programming in Java" equals "programming", and there is nothing useful to be learned outside. Or one can learn beh...
Compared to many of the people reading this, I've not participated extensively on LessWrong. In fact, I created my account only about a week ago. That said, I have read many LessWrong articles by contributors such as Eliezer, Jonah, Yvain, Gwern, and many others (if I missed you, my apologies). I wouldn't say it was a huge transformative experience. But I have probably learned a bit more from LessWrong than I learned sitting in on a class by Nobel Prize-winning economist Gary Becker on human capital (without formally registering for the class or doing the coursework). I've learned more of value from LessWrong than all the MIT OpenCourseWare lectures I've consumed. There are a few online experiences, such as reading EconLog, that have been more educational for me than LessWrong, but I can count these on the fingers of one hand.
Some of my friends have claimed that reading LessWrong systematically (and perhaps participating in the comments and attempting to write posts) would generate more value for an undergraduate than a typical core college class (with the possible exception of technical classes specific to the person's major or area of specialization). I'm curious about whether readers agree with this assessment. Do you feel, for instance, that LessWrong provided you with more valuable human capital than your introductory general chemistry sequence? What about comparing LessWrong with an undergraduate "intro to philosophy" class? Or an undergraduate intro class on the history of economic thought? At what percentile would you rank LessWrong relative to your college classes?
A second related question is whether there's a possibility of building a college course -- or college-like course, perhaps a MOOC -- specifically revolving around mastery of the content in LessWrong (perhaps starting with the Sequences). Would such a college course be possible to design in principle? How would such a college course compare with core requirements for undergraduates today?