As far as I can tell, several things can explain how they fit a whole library in a single book (assuming 50 lines per page, 400 page books, 10.000 books in a library). First, the use of dedicated languages instead of C and C++ seems to explain 2 orders of magnitude. The 2 remaining ones are explained by feature creep and plain lack of reuse (in the Franck system for instance, they use a single library to draw everything, from characters in a word processor to the frames of the windows.)

They also claim specific achievements: a full self-implementing compilation stack in less than 2Kloc, on top of which implementing something like Javascript or Prolog takes less than 200 lines (see http://piumarta.com/software/maru for actual code). A Lex/Yacc equivalent in 400 lines or so (see http://www.tinlizzie.org/ometa/ for actual code). A Cairo equivalent that run with acceptable performance in about 500 lines. A TCP-IP stack in 160 lines, stable enough to run a web site.

If half of that is true, we can effectively talk about a silver bullet. That bullet won't kill the complexity werewolf of course, but it will seriously cripple it.