Things can get rather monotonous shooting centerfires at 300 yards unless you're in competition with yourself or others for small groups. If you're into measuring groups than they might be just right for you.
But don't you believe any of the garb about the rimfires being limited. Shooting rimfires, specifically the .22lr, out to 300 is not only doable but great practice for 1000 yard centerfire. As a matter of fact it basically negates the need or want to shoot LR centerfire. Why shoot expensive ammo at 1000 when you can shoot cheaper ammo at 300 for identical difficulty, principles and tactics.