Why destroyer flotillas needed leaders

Were flotilla leaders mainly command ships, or simply more powerful destroyers?

They were principally command and administrative ships, though purpose-built leaders were often larger and carried additional armament.

A flotilla leader's extra size and armament supported its command staff as well as its combat role. Tribal-class destroyers complicate recognition because every ship had the size and power associated with a leader. The organizational requirement therefore explains more than the silhouette or gun battery alone. It also shows why a leader could be difficult to identify once ordinary destroyers grew larger.