High Sierra missing openssl manpages
These manpages are missing for me as well on macOS High Sierra 10.13.6 (17G65). I also noted that some manpages are outdated and incomplete (for example pmset is from 2012, lacking some details).

However I do have some manpages via MacPorts (e.g. OpenSSL(1)).

I have these paths in /private/etc/man.conf:

MANPATH /usr/share/man
MANPATH /usr/local/share/man
MANPATH /usr/X11/man


(the latter two are non-existent), and these in /private/etc/manpaths:

/usr/share/man
/usr/local/share/man


(the latter again non-existent).