Most feral hogs aren't 400#. I've killed a lot with a 222 rem. A 223 works just fine too. The majority of hogs are probably better classified as pigs (50-150#).
Of course we don't ever have to justify or have justification for owning one kind of firearm or another, but one. The only justification is the 2nd Amendment which articulates our right.
It's a slippery slope when we start buying into the left's argument that we must have or prove a need for any right.