Games don't compete on concept, otherwise there would only be one RTS, or one FPS. Games compete on art, story, level design, and game mechanics, among other non-game specific components like marketing, distribution, and pricing.

Realistically, a concept alone is not sufficient.

I bought Threes, then moved to 2048 because while Threes had components like cute tiles, fun voices, and features like showing the next tile, it was still simply easier/quicker to open a new tab and play from there.

Does the existence of Diablo mean that we don't want Torchlight?

Does the existence of Modern Warfare 2 mean we don't want Spec Ops: The Line?

Games can be very similar to previous ones but still offer a new experience.

Flappy Bird is the same concept as "helicopter game", and others, but the gameplay is novel to the extent that it's maddeningly difficult. And the pipe design is a blatant Mario ripoff. A rule banning derivative games could have easily caught Flappy Bird in its filter.