Awful AWFUL Idea. It funnels players into the top ten/fifteen alliances and honestly what's the fun in that. The more alliances in the game, the more in depth the politics are.
Protectorates are a thing, it creates the need for smaller alliances to reach out to larger ones in order to be successful.
The problem with this idea is that it would essentially remove middle tier alliances and there would only be top ten, and everyone else. Not fun in any way.