Why are anatomical structures most often used when constructing a dichotomous key?

Why are anatomical structures most often used when constructing a Dichotomous Key? The structures are used because one, they are east to see. Two, they can be preserved. Is it possible to have more than one key to identify the same living organism?

{if this is wrong lmk so i can post a question and give you fr33 p01nts}

123/33

explanation:

because i added numbers

enzyme speed up the reactions