Actually, the idea has merit. Currently, the finals mainly feature core stacks like: archons, monarchs, and skeletons. In the future, stacks like 500 pikemen, 900 master gremlins, 250 dwarves, etc., could compete with them.
This would add variety to the strategies, at the very least, and provide additional interest.
In that case, diplomacy isn't needed; rather, a kind of universal transformer is required, similar to the human castle in Heroes of Might and Magic V.
