this (below) is my intuitive thinking, (and some more
of it can be read at the puff piece at this link:)

in the old days, forks were primitively made and made
of lower tech materials. to combat the ever present
danger of breakage, reinforcements were added inside
the crown as a way of adding a "butted" are to the part
of the fork that normally failed. a thin sheet of metal
is all that is needed to effectively strengthen up the
area, as oppossed to using a heavier guage blade; doing
former safeguards the fork (i think...) and doing the
latter makes it too heavy. and doin' the tighten up makes
me giddy. and eating twizzlers makes mouths happy.