If you don't think the content of that book is relevant to the systemd debate, then you haven't read it. I'd like to see you point to a better book about the Unix philosophy.

http://en.wikipedia.org/wiki/Ad_hominem

I've been using unices for over 20 years now (first was ultrix, then truos, sunos, solaris, hpux, aix, linux, netbsd, freebsd, osx) and I don't believe there is such a thing as a unix philosophy.

Give the Art of Unix Programming and honest read, and I'm sure you will come around.

If you have ONLY used Unices, then I could understand why the philosophy is invisible.

If, like me, you had used Windows exclusively for a decade, and then Unix for a decade, then the Unix philosophy would knock you up side the head. The systems could not be more different. (Despite the fact that they run mostly the same applications. http://www.joelonsoftware.com/articles/Biculturalism.html is the review that got me to read it).

Of course I haven't only used unices, how is that even possible in this world.

That is the interface between the systemd sub-daemons and third party code.

There is no such promise about the interfaces between said sub-daemons and systemd-init.