Why a carrier-sized arsenal ship is difficult to sustain

What would a VLS ship the size of an aircraft carrier be like?

It could carry about a thousand cells, but filling and reloading them would make the ship exceptionally expensive and logistically demanding.

A hull with the footprint of a medium carrier could carry roughly a thousand vertical-launch cells. The engineering problem is solvable, but buying enough missiles to fill the ship would consume an enormous share of most national stockpiles. Reloading VLS cells at sea is also slower and more hazardous than replenishing aviation stores on a carrier. The arsenal ship is therefore a munitions-production and logistics commitment rather than simply a large hull covered in launchers.