Every cancer mage has the exact same niche

It doesn't matter which mage you play. Mostly. All you need to do is land your low-cd cc ability, and once you do, you can just all-in with the rest of it. Oh, I charmed you with my E? Let me just Q W R really quickly. There, you're dead! Oh, I stunned you with my Q? Let me just E R you really quickly. There, you're dead! Oh, I stunned you with my Q? Let me, uh... umm... Hold on, I'm getting into position, umm... Oh, I stunned you and all your friends for a long ass time with my R? Let me just Q E E E E E E E you really quickly, and now let me Q E E E E E your friend. Boom, you're dead! Oh, I stunned you with my E? Let me just Q W R E W Q you really quickly. There, you're dead! Oh, I threw my R somewhere in your general direction? Niceeeeeee. Oh, I stunned you with my E? Ok, cool. Let me just sit back as- oh look, you're dead! What's that? Every ability I use both stuns you and causes massive damage? Let me just use all of them! Boom, you're dead! Oh, I hit you with my tether? Are you unable to flash out of its super long range? Let me just Q W R you really quickly. Boom, you're dead! Oh, I rooted you with my Q? AAAAAAAAAAAAAAAAAAAAAAAAAAAAA!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Oh, I rooted you with my Q? Not all angels are good! NOT ALL ANGELS ARE GOOD! NOT ALL ANGELS ARE GOOD!!!!!!!! Oh, my Q is a reasonable distance from you? Let me just CC you with my massive, MASSIVE hitbox R and proceed to W Q you again. Boom, you're dead! Oh, I stunned you with my E? Let me just walk up to you and Q W R you before the stun wears off. Boom, you're dead! Oh, I stunned you with my E? Let me just W you and nothing else. Literally just my W, because you're an ADC. Boom, you're dead! Oh, I knocked you back with my E? Let me just W Q W R you really quickly. Boom, you're dead! Oh, I managed to stun you with my W? Let me just Q E R you really quickly. Boom! Join the glorious revolution! Oh, I managed to root you from a long distance with my massive-hitbox E? Let me just W W Q R you really quickly. Boom, you're dead! Oh, this girl just makes me sick.

Why does nearly every mage NEED to have hard CC in order for the person playing it to not be trash?