DBus was a joint effort to build a common messaging system to be used in all desktop environments, in particular to get away from the individual incompatible brokers that Gnome and KDE used at the time. Lennart Poettering had nothing to do with this, his first commit was in 2009, 4 years after 1.0 and 7 years after the project was started.
What you are referring to is probably Kdbus, a failed initial attempt to move parts of DBus into the kernel.
What you are referring to is probably Kdbus, a failed initial attempt to move parts of DBus into the kernel.