Sequences contain a rational world view. Not a comprehensive one, but still, it gives some idea about how to avoid thinking stupid and how to communicate with other people that are also trying to find out what's true and what's not. It gives you words by which you can refer to problems in your world view, meta-standards to evaluate whether whatever you're doing is working, etc. I think of it as an unofficial manual to my brain and the world that surrounds me. You can just go ahead and figure out yourself what works, without reading manuals, but reading a manual before you go makes you better prepared.