Take 84 as an example.  I picked up my short essay on Defoe's Roxana from a tray outside my tutor's office this afternoon.  84%.  I ask you, what's that all about?
My mark is one point below a High Distinction grade.  One point.  I'd much rather receive a lower mark - the high-seventies or low-eighties maybe - because the mark would be clear.  Dougie, it would say to me, middling sort of effort.  Must try significantly better.  84 though?  That one point is within a margin of error that has nothing to do with careful assessment.  It's a message - not quite good enough for a High Distinction but very close, almost there, treat this as sign of encouragement, missed it be a whisper.
Aaaaaaaarrrrrrrrggggggghhhhhhhhhhhhh!
Good.  Got that of my chest.