I know a bit about this stuff (three decades in the Army).
It, like several other rounds, was created with the idea of walloping an unarmored biped in room-to-room / house-to-house combat with an AR platform. For that very specific role it would be a pretty good choice as a carbine round. The problem is that the team or platoon's mission the next day might be an ambush along a ridge line miles from anywhere with the likely fight over extended ranges. For that battle a 7.62 would be hard to beat.
Several 458 SOCOMS made it into the inventory of a variety of SOF units for exactly this purpose..
To
@Red Leg 's point.. over time most (if not all) have been phased out of those same units.. They were deployed with varying degrees of success.. but ultimately better options have been found that are are a bit more universal in nature and have more wide ranging capabilities, but can still put the desired whallop on a bad guy or a vehicle at close distances..
To my knowledge they were mostly used at ECP's for the purpose of VBIED/Vehicular attack defense at close ranges..
All of that said.. I own a .458 SOCOM AR (among several others).. for hunting purposes, I think it is very linear.. but.. it does fill one particular role quite well (IMO)..
For hog hunting at ranges of 150 yards or less.. its an absolute hammer.. not only on big boars.. but on sounders...
Youre getting 45-70 trapdoor ballistics (same 300, 350, and 400 gr projectiles thrown at roughly the same speed).. out of a short, lightweight platform, that handles exceptionally well when fired at a fast rate, is easy to get in and out of a stand with, manipulate in a stand or any other tight space (collapsible stock, short barrel, etc).. thats affordable (If you already own an AR, getting a 458 SOCOM running is just a matter of slapping a 458 SOCOM upper to your already owned lower, for a price of about $325..)..
Combine a 458 SOCOM AR with either low cost night vision (ATN X-Sight, or Sightmark Wraith).. and for less than $1000 all in, you have a rifle that can be used day or night, that is nearly perfect medicine (IMO) for when a dozen hairy, rooting, destructive bastards, start tearing up your favorite deer hunting food plot..
Could a smaller round do the same thing? Sure... I also own a 350 Legend AR (similar ballistics to a .30-30).. and a 556 AR shooting heavy bonded bullets like the 64gr SST from Nosler can also do the trick..
But.. not with the same authority the 458 SOCOM provides..
I've seen a lot of hogs/deer get up and run after being hit with 556, 300 BLK, 7.62x39, etc..
I've never seen one move more than 3 feet after being properly hit with a 45-70 or a 458 SOCOM...
The difference is the 458 SOCOM can drop 10x rounds of 350gr TTSX on a sounder in 10 seconds... I dont know of any 45-70 that can do that same thing..