Too much detail is bad in the same way that an intro biology course flooding you with chemical equations for bodily functions (when chem is not a prerequisite), literally <i>hundreds</i> of new terms, many of which are fairly isolated, and a hundred medium-rare diseases is bad.  What do you end up remembering?<p>"Body-stuff is hard."<p>And 90% of what you read falls out of your head in a year, along with 90% of the useful stuff.  If it's trimmed down, you may lose 50%, and 50% of the useful stuff, which covers <i>all</i> of the generally useful stuff in the massive 10-kilo textbook that covers more than a biochem grad student remembers.<p>Fewer relatively-unrelated (or seen-as-useless) facts also make it easier to form logical connections with the remaining facts, which help you remember and apply what you've learned.