Armoured cruisers on the path to all-big-gun armament

Why was the all-main-gun concept first associated with battleships rather than tested on an armoured cruiser?

Some armoured cruisers were already close to the concept; the Duke of Edinburgh class is his example of the transition.

Some armoured-cruiser designs were already moving toward the all-main-gun principle. The Duke of Edinburgh class comes close when its battery is examined carefully. Battleships made the concept most visible, but they did not develop in isolation from cruiser practice. The transition was a broader design movement rather than a clean invention confined to one ship type.