What is the purpose for stage direction

Stage directions serve many functions, but their primary purpose is to guide actors' movements on the stage, called blocking. These notations in the script, written by the playwright and set aside with brackets, tell the actors where to sit, stand, move about, enter, and exit

a woodchuck would chuck as much wood as a woodchuck could chuck if a woodchuck could chuck wood.

: ) most likely not the right answer but why not put a good dad joke up in there?