As noted in the comment, these include a few quite strong ones:
- sshd(8) will only allow in "wheel" and "users" members
  by keys, no password access is allowed;
- password change even by root is subject to quality checks;
- su(8) is only useful to lower privileges and not gain those
  (so root access is available either through local console
  or via use of ssh keys).

Don't use if frowned upon.