I should have mentioned that
sudo
preserving home is Ubuntu-specific in
that answer originally. I was unaware of this at the time, though. Or perhaps at that time it wasn't just Ubuntu in which
sudo
preserved
$HOME
; that is, perhaps at the time other OSes I used had versions of
sudo
that were based on old upstream versions or that were patched like
sudo
in Ubuntu was patched. That might explain why I never noticed this.