Why a more successful Taranto raid would not automatically remove Italy

Why would a much more successful Taranto raid not necessarily knock Italy out of the war?

It could trigger conditions for an Italian political collapse, but naval damage alone would not erase the Regia Marina or guarantee every later event.

Permanently disabling the Italian battle fleet could accelerate victory in North Africa and weaken Mussolini, possibly producing a change of government. Control of the southern Mediterranean shore could then shorten and protect Allied supply routes to Gibraltar and Malta. Yet each step has alternatives, and the surviving Italian Navy would still include cruisers, destroyers, submarines, and potentially a battleship shielded by the harbor geometry. An Italian exit is plausible under these conditions, though it is far from automatic.