But you still need to do the server side valuation.
Yes, but from the end-user perspective, it's nice to not have to do a round-trip to find out that you entered something wrong.
Fair enough.
Still, validating a form client-side doesn't require a JavaScript framework; it would only require the server to send small snippets of JS for each field with the form.
That doesn't detract from the value of client side validation, which is that it will be faster from the client's perspective and reduce server load.