This is not quite universal! My wife in particular does not like assigning people on how to help her, as that is additional cognitive load on how to make someone useful to you, she much prefers people either stay out of her way, or help by just looking with their eyes and see what needs to be done.

Do agree they need to know what they are doing too, having someone who doesn't know how to chop veggies the way you like them and just start doing is definitely no good, but after sometime cooking with your partner you should know what needs doing and how to do it.