Looks great, but why?

Why choose a limited capacity cartridge that was specifically designed around the size restrictions of a specific platform (AR15) and build a bolt gun for it when there are soo many better cartridge options that you can use in a bolt gun? It's akin to building a Fast-Five Shelby Cobra kit car and then putting a 1.0L 3-cylinder Ford Fiesta engine in it.

To each their own, but someone please explain the logic to me? Guys have done it with the Grendel, the Valkyrie, and now the ARC when they could have gone with a 6.5 Creedmoor or 6.5x47 Lapua, a .22-250 or .220 Swift, or a 6mm Creedmoor or 6x47 Lapua or a .243 Win or a .243 Win AI.

JUST TELL ME WHY!!!!!!!!!!! WHY LIMIT YOURSELVES!!!! I DON'T UNDERSTAND IT!!!!


(Over dramatic attempt at humor aside, I'm honestly am curious why and hope you will enlighten me.)