pramodvu dbus-activation is sanely supported only by systemd
And by sanely supported, we actually mean redundant. dbus activated services predate systemd, but there is essentially zero reason to use dbus activation when you can instead go for user level units.
I understand Arch peppering all of core with a systemd dep since it is, after all, a systemd distro. What I don't get is why people think it's a good idea to add systemd-libs to something like signal-desktop. I have been building that package locally for a few weeks now because of this improvement.
The unimproved version seems to work without any difficulties, so one has to wonder what was the original intent behind the change.