I'm a big fan of "reading the reference", but documentation often does not cater to that use case anymore. Instead of curling up with an authoritative book (like the Perl, Python, C, or C++ books, the dtrace book, or the O'Reilly X11 or BSD reference manuals), I get to, in the better case, click around a 1000 page web site, or, in the worse case, watch 50 videos covering 10% of the functionality.