Why navies retained paddle warships into World War II

Why were paddle combat ships still used in the world wars?

They remained reliable and fully adequate for coastal convoy escort, maneuvering, and minesweeping at the speeds those missions required.

Navies do not discard reliable machinery merely because a newer system dominates frontline warships. A 20-knot paddle vessel could still keep pace with a coastal convoy, maneuver effectively, and sweep mines. These were demanding but bounded missions that did not require battle-fleet speed or oceanic efficiency. In those roles, mission performance mattered more than whether the propulsion looked technologically old-fashioned.