Capability matters more than displacement labels

Why do some navies appear to have frigate and corvette captains but no destroyer captains?

The apparent gap can reflect rank terminology, and the ship label itself depends on national usage; destroyer-versus-frigate classification should consider capabilities and mission, not displacement alone.

Corvettes and frigates may be commanded by officers holding ranks translated as lieutenant commander or commander, while a destroyer commanding officer may simply be a captain. The shield-and-spear distinction also matters: a ship retaining Harpoon, torpedoes, Tomahawk, and other offensive options behaves differently from one refitted mainly for defensive duties. National naming practices vary, so weapons and operational role provide essential context for the label.