pistol caliber carbines come into their own in short to mid range. less recoil and better energy dump is where a pcc can come in over a rifle caliber like .223. given its a specific set of circumstances where a PCC has advantage. but there are times where they do exist. .223 is likely to go through and through at short ranges where the pistol round is going to dump all of its energy inside the target. plus pistol ammo is almost always cheaper to shoot than rifle.
I havent spent much time with 357 sig. but i love by friends 9mm hipoint carbine... if it were a 10mm i could see it as a good brush gun for coyote, fox, or things like porcupine(hard little suckers to kill).