You played it perfect, you landed all your telegraphed skillshots...
And you did maybe 1/3 - 1/2 of their health (and if you happened to catch them when they were low, they have Maw of Invincibility and Nullifying Orb to cover their ass anyway). Then, when your CC wears off, they turn around, right click on you, and guess what? You're dead within 2s. Nothing you can do about it either, since AD champs can't be dodged, and they're all faster than a silly mage or other AP champ -- plus, you actually have CDs, unlike autos.
But that's "fair."
Maybe one day people will stop just putting up with shitty companies, and EA, Activision, NCsoft, Aeria, Nexon, Riot, and even Nintendo now will just fade away, so that devs who actually care can fix things.