Until I started up the server.
Once I started the server, I noticed the following message:
HTTP Server: Using Web Configuration ViewI hit the web and came up with this IBM technote, "Httpd.cnf deleted during Domino server upgrade.".
HTTP Server: Unable to read httpd.cnf
HTTP Server: Shutdown
But I didn't do an upgrade. It was a fresh install of Domino 8.5.1, but low and behold, that was the issue. I didn't install "Web Services Data Files" originally, but did in fact need them. I went back, re-ran the installed and selected it.
The HTTP server now starts.
Another lesson learned.