PATH: /usr/local before or after /usr ?

[Alan Somers]

FreeBSD has always placed /usr/local/X after /usr/X in the default PATH.
AFAICT that convention began with SVN revision 37 "Initial import of 386BSD
0.1 othersrc/etc".  Why is that?  It would make sense to me that
/usr/local/X should come first.  That way programs installed from ports can
override FreeBSD's defaults.  Is there a good reason for this convention,
or is it just inertia?
-Alan