I would disagree with this, from personal experience. I am intelligent enough that I could have figured out these things if I thought about it hard enough and long enough, but I had not focused my attention here until I read these articles. Eliezer did a great job of expressing things that I had not thought about yet, in ways that I can understand.
Of course, I’m not a random person on the Internet (literally random, that is), so that is worth taking into account when deciding whether the person you are talking to is likely to understand. Some posts are easier to understand than others, but overall I have been impressed with how accessible the Sequences are.