I just confirmed that completion from `~/.ssh/config` **is working** with a vanilla Zsh install (Ubuntu package version 4.3.17, without OMZ installed of course). Can you confirm that Zsh does not complete from `~/.ssh/config` on your machine, and share your configuration?

I just browsed quickly through [Zsh completion code](http://sourceforge.net/p/zsh/code/ci/master/tree/Completion), and I could not find where this is done, but `~/.ssh/config` is definitely parsed for `ssh` completion. Will look into it later.