I replied:
It’s super simple to manage on systemd systems by using slices to limit all processes a Unix user starts. You just need to add a drop-in to the systemd config directory and reload the daemon.
To be clear, the whole setup is as easy as creating a slice for a UID.
# /etc/systemd/system/user-1000.slice.d/10-limits.conf
[Slice]
CPUQuota=20%
MemoryMax=500M
…and, running systemctl daemon-reload—this is something we could easily implement.