My guess is that those are a lot of packages that are meant to be intermingled with each other, but is done in such a way like tangled knots. It's proven that that much interweaving between applications is not necessary for full function.It's all I've ever used, fvwm2 specifically. Have yet to figure out how I could benefit from a desktop environment. Isn't that kind of a Linux or Windows idea? You know install and go. Have yet to find something I couldn't do with a window manager and the addition of one or more packages.
libcanberra for instance sends basic sounds out from applications, but it wants to add a graphic display banner in a way, that is not output only, so the messages go back and forth when not needed, and dependencies recursively go back and forth between graphics and sounds.
Dbus seems to go back and forth between applications, sending messages back and forth. Really, a like application would have everything output to it, for essential processes like printing and scanning, and be simplified, then everything that needs to know the status links to it from one point, instead of so many, because each application wants its own controls.
Maybe, desktop developments have constant reinventions of the wheel, especially on Linux, so there's redundant applications that do the same thing, then they try to link back to each other.