pls tell me I'm wrong about 1/3 crit chance

the set up is Warlock Hexblade with Eleven Accuracy and Devilsight+Darkness combo for on demand advantage

Hexblades curse let's you crit on a 19 and 20 (single target). so 2/20 crit chance = 1/10 cc.

with Eleven Accuracy you essentially roll 3d20, 3 chances at a crit. then isn't this a one in three chance to crit?

I gotta be wrong. otherwise everyone would have been talking about this already.

thank you for your attention.