Systemd does standardize many interfaces[1] (including logind).
[1] - http://www.freedesktop.org/wiki/Software/systemd/InterfacePo...
[1] - http://www.freedesktop.org/wiki/Software/systemd/InterfacePo...
Ian Sutton, who embarked on a project to emulate some of the systemd D-Bus daemons, also attests to the "standardization" being largely a red herring: http://darknedgy.net/files/systembsd.pdf
I'm not sure I get how those slides indicate that the systemd interfaces are not standardized (with the possible exception of timedated, although the slides were kind of vague). Most of the problems seemed to be due to the fact that OpenBSD doesn't support PAM. Was there a particular section you were referring to?