I see that gradient considered,

my first thought was that it was perhaps because programmers think in binary.......

Some programmers do think in binary, or octal, or hexadecimal, or bi-quinary ...
but the actual problem in this case is how they count ... do they count from -zero-
... or from -one- or some other beginning?  ... and if more than one programmer
works on a project, do they all use the same starting point???

On a philosophical note, will my opinion about the error count? 
... with the renderosity programmers, that is.  [sly grin]

--
Martin
p.s. Why am I thinking of The Count from Sesame Street?