I think top posting can possibly make sense if two
people
are carrying on a (private, two party) discussion and can
remember the last thing they said to each other, etc.
or if you are using a threading mail reader so you have don't
have to keep on reading the same stuff and scrolling down to
find the replies.
Yes - not all the logic is on the side of the old faithfull.
Of course, with adequate trimming either method is usually satisfactory ...
but that is a big proviso.
Andy