>>106368846
I was forced to use them because back then I was using my Android phone's internets and that particular Android system picked an arbitrary IP from the 192.168.42.0/24 or whatever the subnet was.
So the idea was I could keep using DHCP *and* make systemd-networkd do routes based on that arbitrary gateway address. In any case it adds more flexibility even if your router didn't change IPs all the time.