It doesn't look like gnus-setup is being required anywhere.  Am I
supposed to require this myself in .gnus.el?

I noticed this because when I stopped manually setting
message-cite-function, it was being set to message-cite-original, even
though from gnus-setup.el, which I assumed was being loaded, it
definitely should have been set to sc-cite-original.

I'm sure I'm just missing something here.  Someone hand me a clue.