The grandparents comment was targeted at cgroups in general. You can’t use cgroups without cgroups. To add on that: IMHO, both systemd and docker made cgroups much more accessible to joe sysadmin and while they’re not a bulletproof security feature, having them (and capabilities, another kernel feature exposed by systemd) in wider use is generally a good thing.
Sure, then you need to write scripts to monitor your daemons and their dependencies, and you may end up writing something likely worse than systemd that just suffers from the 'NIH' syndrome.
Adjusting to systemd took me a while, but I believe it was worth the effort, and I also believe most people who dislike systemd are just set in their old ways
Them being released at similar times does not mean systemd implemented them, they exist completely separately to systemd.
Literally:
is all you need for cgroups.