theres some questionable quality content in the book, but lets be fair 4.5k pages is hard to manage. if people dont get too 'anti' about it, it might grown into a good book at some point over editions. It would certainly be useful to have such a book be complete and maintained (tons of work ofc). personally id prefer a book that requires abit more prework, like learning C etc. and Unix, so it can be more compact spec…
I used to point at LFS/BLFS in the past (Linux from scratch), since the idea is great. Unfortunately they are now systemd-only, which kind of defeats some of the points, IMO. But documentation is useful, so FreeBSD improving here is good. Perhaps one day it can compete against Linux again. :D