Caliban does not suck though, he just plays fair
Yes in the world of Revenant and Dante where immortality and just ignoring core balance mechanics like self-stagger he does "suck"
But his kit has fair shield gating, one of the best tools for armor removal, damage enhancement and an easy slot to play around with Helminth
He can solo Netracells with an active playstyle pretty comfortably, thing is Dante can do it with 4 mods, no potato installed and standing still
Caliban is a well designed, well balanced frame in a game where you can just ignore half of the skill ceiling by just picking one of the handful frames that don't play "fair"