I don't know math, quantum mechanics or philosophy
Perhaps I'm used to read on, even if I might miss something. I know a bit of math, and there are a few posts that benefit from that, but only a few. I don't know much philosophy either (except the sequences, of course).
i had to open 10-20 pages of references and google searches to follow what was going on(per individual sequence page).
Let's take Making Beliefs Pay Rent (in (Anticipated Experiences) as an example. What would you have to look up there? And don't say "colonial alienation" ;-). For me it might be phlogiston and elan-vital. But A) understanding those words is hardly essential for understanding the post and B) they are explained somewhere else in the sequences (I never said navigating them were easy).
Its also strongly aimed/influenced by american culture, so some things are weird for us Europeans.
I'm European and I don't really know what you mean.
i have tried the read-on thing on 2 pages and it made it even worse, so i dropped back to the opening pages tactic. That page you mention is actually one of the better ones although using examples like "Wulky Wilkinsen" and post utopianism made no sense to me. Having things explained elsewhere is a big problem imho, but i intend to devote some time to help fix that.
You may have been exposed to enough american culture by tv, movie, shows and books to not get overwhelmed by them?
Iksorod and I made a Google doc of intro-level training materials for rationality / critical thinking. We'll keep adding to it as we find more stuff. Please comment with your own additions.