Seems strange to me too...I had been troubleshooting the sshd.service issue for two days. There was no logs, nothing. I was just hitting the wall. I tried a lot of combinations to get it to work but all failed.
The sshd.service was starting, if I manually did a systemctl start sshd.service. But always failed at startup. At times it would start and then get a signal 15 terminating and would close the daemon.
After not able to resolve the issue, I started checking all the other services. Every other service was starting at bootup just fine except sshd.
Not finding anything else to troubleshoot. I happened to stumble upon the sshd.socket and the Conflicts part of it. Did a hit and trial and it worked. Technically I still am not sure as to why..