As he should. These things are all stupid. They're monstrously stupid minutiae that you shouldn't have to know about unless the abstraction somehow leaks.
What he's saying is, "Where are better abstraction mechanisms?" And that's a tremendously important question (whether you get it or not).
Application messaging is a great idea. Desktop buses are useful.
DBus as an implementation of messaging largely sucks. It uses an ad hoc protocol, there's little security, the C library implementation of it is a big mess, the socket interferes with remote X, introspection doesn't really work, and it uses far too much XML.
dbus
/usr/lib
Boost
ioctls
SMF
signals
volatile variables
prototypal inheritance
C99
dpkg
autoconf
LD_LIBRARY_PATH
/usr
zombie processes
bash tab completion
dynamic linking
static linking
glib
the details of programming languages
formatting source code
configuring window managers
configuring editors
unicode
directory hierarchies