I restarted by laptop today which is running archlinux because pacman was complaining about a corrupted db. In the past when some package or another get's upgraded, I often have to restart to fix the problem (very un-linux like).
Anyway after restarting, I always have to run "sudo netctl start eth" to get networking working again. Today I noticed a string of options for netctl and the "enabled" or "is-enabled" caught my eye. I tried "sudo netctl is-enabled eth" first which gave me an error, so I tried "sudo netctl enable eth" after which the former command gave me "enabled".
On a whim, I restarted arch and on reboot, I found that the nic was already enabled! One small triumph over systemd's attempt to hide functionality behind complexity.