Well by your reasoning they never should have been allowed inside in the first place, and I agree. However, it's too late for that. We could just nonchalantly observe that the town asked for it, but that would be cruel towards the townspeople who are now struggling in the aftermath. The point of this piece is to highlight the effect it had on the locals, how it just left without any responsibility towards the drain it caused. The point isn't to somehow change Walmart's character as a corporation, but rather show others that maybe they shouldn't welcome a devil in disguise despite what it offers, that maybe they should support local businesses and focus on self-sustainability.