It is easy to build something and say "this helped family X, or this powered Y homes", but there are so many externalities that are simply hidden. What if family X is part of Nation Z, who is about to start thermonuclear war W?
It's just a guessing game at that point. It seems that most people ignore it under the guise of "well, I do the good that I can", but it's false comfort, IMO.
It's better than the alternative, which is to assume that any job that pays (and thus is from a company that earns profit) has equal impact or externalities with all other companies.
A lack of clarity shouldn't be an excuse for not trying.