This is a more a note that the systemd adaptor doesn't constrain CPU or memory, incase others are looking at using it.
However controls can be added with the AllowedCPUs and MemoryHigh or MemoryMax (probably this is desired) options in a service file.
Spec URL: https://www.freedesktop.org/software/systemd/man/latest/systemd.resource-control.html
(Reminder for myself to investigate and implement.)