LW has a problem. Openly or covertly, many posts here promote the idea that a rational person ought to be able to self-improve on their own. Some of it comes from Eliezer's refusal to attend college (and Luke dropping out of his bachelors, etc). Some of it comes from our concept of rationality, that all agents can be approximated as perfect utility maximizers with a bunch of nonessential bugs. Some of it is due to our psychological makeup and introversion. Some of it comes from trying to tackle hard problems that aren't well understood anywhere else. And some of it is just the plain old meme of heroism and forging your own way.
I don't quite know how to make this response more sophisticated than "I don't think this is true". It seems to me that whether classes ore lone-wolf improvement is better is a pretty complex question and the answer is fairly balanced, though overall I'd give the edge to lone-wolf.
Yeah, that seems to be the biggest flaw in the post. I shouldn't have addressed it to everyone, it's intended mostly for people suffering from "akrasia". I.e. if lone wolf is working for you, ignore the post. If it isn't, notice that and change course.