Why multihull carriers lose too much internal volume

Why is a multihull design unattractive for an aircraft carrier?

It gives up too much internal volume for hangars, weapons, fuel, and machinery.

A multihull carrier may gain stability, but the design sacrifices too much contiguous internal volume to justify the trade. The flight deck is only one demand: the hull must also contain the hangar, aviation weapons, fuel, and engineering plant. Splitting the displacement among several hulls makes those spaces harder to arrange. Carrier design favors a large continuous volume beneath the flight deck over an abstract stability advantage.