They literally are, though. The main advantage of a rifle is its greater range, which is irrelevant in close-confines. AR-15's also typically fire an intermediate cartridge, which has a lot less stopping power than say a 12 gauge shotgun firing even triple aught buck, let alone a slug, or a .45 revolver round. An AR-15 is a varmint rifle; in my state you can't even legally hunt deer with a .223 because it's inhumane to hunt a 100+ pound animal with such a weak weapon, you'll just end up wounding it.