Why distant-station sloops had senior commanders

Why did such small ships need relatively senior commanders?

Their independent diplomatic duties and occasional role as an admiral's mobile headquarters required experienced commanders.

Sloops operating far from support represented Britain directly and therefore often carried full commanders. As the China Station commander-in-chief's yacht, HMS Falmouth could place her captain in the role of flag captain and de facto chief of staff when the admiral was away from the cruiser. Rank followed responsibility, not simply displacement.