if you needed a reason to exit this subculture, here are several dozen including the cult of genius, ingroup-overtrust, insularity, out-of-touchness, lack of rigor, and lack of sharp culture that exists in the current environments.
timestamps are included so that you can skip around each video topic.
finally, there are 34 references in the description. I would have included more but this exceeded the character limit.
I agree that LessWrong is not an exclusive source of most/all ideas found here.
I think this means less than (I think) you are trying to suggest. For example, right now I am reading a textbook on set theory, and although I am pretty sure that 99-100% of the information there could also be found in other sources, that it not a sufficient reason to throw the textbook away. There are other possible advantages, such as being more accessible, putting all the information in the same place and showing the connection.
Another important thing is what is not included. Like, if you show me a set of people who read "Thinking Fast and Slow" and "Predictably Irrational", I would expect that many of them have also enjoyed reading Malcolm Gladwell and Nassim Taleb, etc. You know, these things are a genre, and yes if you read a lot of this genre, you will be familiar with the good ideas in the LW Sequences. But the genre also comes with a lot of strong beliefs that do not replicate. (Talking for 10 minutes with someone who reads Taleb's tweets regularly makes me want to scream.)
Then, there is the community. Reading the books is nice, but then I typically want to discuss them with someone. In extreme case, discuss the ways how the things we learned could be applied to improve our everyday lives. (And again, what is excluded is just as important as what is included.)