There were better ones. All of the examples I listed were improvements over sysvinit. Again, it's not explicitly supporting one scheme over another. It's more

There were better ones. All of the examples I listed were improvements over sysvinit. Again, it's not explicitly supporting one scheme over another. It's more like provide a generic event queue over some channel (stream, Netlink, etc.) for processes to consume and be able to exec(3) processes in response to received events. Much like how udev consumes kernel uevents. Yes, D-Bus system bus activation assisted in lots of desktop subsystems. Your statement that "D-Bus and hald was our systemd" doesn't make any modicum of sense, nevertheless, and is simply conceptually confused. You're really painting broad strokes and taking liberties with the way you categorize things. I don't like poisoning semantics, it's a very dirty game. (As a side note, an "activator" is any program that conditionally exec(3)s a binary in response to an IPC event. Something as simple as "mkfifo /path/to/pipe && sh -c 'while true; do cat /path/to/pipe >/dev/null; /path/to/program; done' &" is an activator. It's not rocket science.)