Well I'm afraid I cannot duel your friend, he's not on EU, and I'm done with all the e-peen US players are better thing.
That same logic you mention applies to the other side too. Any skillful WD will be able to manage his cooldowns and force monk to use his by means of haunt. If I use the environment properly he won't be able to 1shot me before he takes 1 haunt. And with the amount of dmg used in a haunt build, 1haunt = death if he doesn't pop serenity.
That said, I have always said that banning haunt will maybe favour Monks strongly, once they get used to playing no-haunt wds. And thats why we need tests, and test league, etc.