The page is half the campaign
A great ad pointed at a weak page is money converted into disappointment. Half the accounts we audit are not suffering from bad media buying at all; the click was fine, and then the page lost the visitor. Slow load, buried offer, a form that asks too much too early, no reason to trust.
We build pages the way we build ads: around one action we want the visitor to take, with everything on the page either moving them toward it or removed.