That's misrepresenting FORTH considerably I think. The data available to a forth primitive is typically on the top of the stack. That's just the same in every other language, it's just a parameter passing convention that most languages share. The problems with trying to write image processing code with FORTH is that pushing an image on the stack or modifying it in place somewhere in memory is a bad match with the language primitives. So you then have to do a whole pile of plumbing to abstract out that little detail.

FORTH excels at control jobs and other embedded tasks.