Why is it that whenever I read an article that describes using a chisel for
something, the chisel always has to be "sharp"? "Clean out the mortise with
a sharp chisel." "Square up the corners with a sharp chisel". Why does
everyone, it seems, single out chisels as the only tool that needs to be
sharp.

I never see them say or write, "rip into strips on the table saw using a
sharp blade." "Flatten the boards on the jointer using sharp knives.",
"Run them through the planer with sharp knives installed.", "Use a block
plane, with a sharp blade, to clean up the edges."

It has always struck me as odd that writers and authors always mention
"sharp" when discussing the use of chisels and not other tools. Is it
really more important for a chisel to be sharp than any other tool?

Just an observation.

Mike