As I opened this article, I thought "I bet this is going to be related to some Goddamned systemd change". And sure enough, about halfway through: > This interface has an IP alias, set up through systemd's networkd. The amount of pain and headache this init-kitchen-sink-wannabe- thing has caused me day-to-day is incalculable.
I remember using iproute2 to add multiple IP addresses to devices at my very first job in 2007. systemd didn't even come out until 2010.