And the social responsibility arises from shaping the local economy in such a way that a large number of people become dependent on the company. If a company becomes the main employer in a small town, it automatically takes on some responsibility. This is less true today when most people know they're not going to work for the same employer until retirement but it is still true for traditional companies with that kind of legacy.
It's not about some theoretical ethical responsibility for the greater good of mankind but about taking responsibility for your actions and the effect they have on people you have built a relationship with. If Industrocorp, Inc builds a factory in Podunk and the labour demand raises the number of residents by an order of magnitude, then relocating operations and firing a large number of staff will ruin the local economy the company created.
I'm not sure how that concept is difficult to understand: your actions have consequences, ergo you are responsible for the consequences of your actions. Large corporations may be amoral, but the CEO of a privately owned company deciding to offshore half the employees isn't. Especially when the company periodical repeatedly claims that the employees are valued and their families are important. This makes the CEO an asshole. Period.