but even intermediate HTML5 can be learned in no more than two I believe.
You have to remember that attributes come into play and not just elements. Also, not all browsers are compliant so that takes a learning curve as well. This is usually the case for CSS. Once you learn those things, sure, it seems simple enough but just remember when you were first starting out how everything seemed so complicated (e.g. what to use, what not to use, what to do, what not to do, etc).