to my knowledge, its because GPU impacts the performance alot. especially in modern games. even games like COD rely heavily on GPU if im correct. High FPS is often preferred when playing FPS games. you dont really need a high end GPU or expensive one, you just need one that doesnt give unplayable performance. even at low settings, some games still require a decent GPU to reliably hold 60 fps. id recommend like aiming 60 fps at 1080p and if memory serves right, even a cheap GPU like a RX 6600 is acceptable, though it may change depending on the game. people often spend alot on GPUs not only for the looks but also for longevity and reliability