One more thing: D-Bus has the concept of generic services which can be automatically started, e.g. org.freedesktop.FileManager1. When you send a command to that service, the file manager will be started if it is not already running. However, there is no mechanism for the user to select which file manager to start, so if you happen to have both KDE and GNOME installed you have a 50:50 chance of launching dolphin or nautilus. See for example: https://unix.stackexchange.com/questions/778028/set-a-specif... . It truly boggles the mind.
D-Bus has no concept of generic services. People are using D-Bus to get automatic startup of generic services even though it's not fit for this purpose. It's quite a different thing.
You could build a viable solution on top of D-Bus though, it's just that apparently nobody bothered so far.
