It can even start the receiving daemon if it is not yet running.
We have a tool for that, it’s called an init system.
The init system is for trusted system services that can talk directly to hardware. Unless you are working on a single-user system with no security concerns of any kind, you might consider using init to launch persistent user land or GUI processes.
DBus is for establishing a standard publish/subscribe communication protocol between user applications, and in particular, GUI applications. And because it is standard, app developers using different GUI frameworks (Gtk, Qt, WxWidgets, FLTK, SDL2) can all publish/subscribe to each other using a common protocol.
It would be certainly be possible to establish a standard place in the /tmp directory and a standard naming scheme for sockets and temporary files so that applications can obtain a view of other running applications and request to receive message from other applications using ordinary filesystem APIs, but DBus does this without needing the /tmp directory. A few simple C APIs replace the need for naming and creating your temporary files and sockets.