In my experience all serious electronics/electrical engineering learning material is written like this, as if the student knows everything about electronics exc

In my experience all serious electronics/electrical engineering learning material is written like this, as if the student knows everything about electronics except the one topic the author is explaining. Probably an artifact of being written for industry users. You can get used to it though, kind of putting boxes around certain circuits and just looking at behavior without asking how it works until you need to understand then doing a deep dive.