Really? How is it supposed to work then, when games have hardcoded vsync or adaptive vsync in them? Is this supposed to overwrite it somehow?

Games never did and never will hold full control over image buffers, their count and method of swapping between them. Everything can be overridden by any wrapper library, DirectX and finally driver. All driver level optimizations are done by altering/disabling effects (ignoring in game settings). Did you never use RadeonPRO/ATiTrayTools? Because someone who did use those would never need to ask. Have you ever checked CCC and it's VSync options? Why do you think it is there?