This is the first thing that came to my mind while watching the video. Web development has become so overly complicated. I believe it is mostly due to working around limitations of the platform and the lack of a de facto standard of how web development should be done. In contrast for smartphone development, largely speaking, the way to do it is the way Android and Apple provide. The web has no single vendor to dictate that and what we have now is a result of that.
I think a lot of it is a lack of documentation. This has two effects.
1) People just get started and get used to not really understanding the interface they are working with. Who hasn't felt like they were playing whack-a-mole with CSS layout? This means lack of conceptual clarity fails isn't notable.
2) Nobody ends up noticing just how complex the rules are.
It was 9 years from when I started looking for a tutorial like http://book.mixu.net/css/ to when I actually found it. That is...really quite bad.