From what i've learned today, there are two ways one can go about validating input.
One is the #element_validate field which is passed along the form hook, and the other is the validate hook.
Why use the validate hook if input can be validated with the #element_validate field? Is it a necessity to implement the validate hook in this case?
Or is it a method that should be implemented for complex validation while all simple validation(is number, is date, is url) can be done via the #element_validate option?