Without treaty categories, heavy cruisers might remain armoured cruisers

Would the heavy cruiser category have emerged without the naval treaty system?

The ships might still appear, but navies would more naturally have continued using the term armoured cruiser alongside light cruiser.

Heavy cruiser is treated here as a diplomatic and technical label rather than an inevitable naval term. A navy could still want a large cruiser with 9.2-inch guns without adopting the treaty-era category. In that setting, light cruiser and armoured cruiser would provide a more organic distinction. Arms-control language can reshape the names applied to warship types.