The glorification of the term altruism is nothing more than the poor understanding about how the human species operates. We will help others only when we have our asses covered. If we find ourselves going the extra mile is because of some cultural upbringing or even religious belief that aims towards a specific behaviour.
I otherwise agree with your post but I'd say that the glorification of the term altruism is part of that cultural upbringing that motivates us towards the specific behaviors that our cultures consider altruistic. In other words, it is useful bullshit that motivates constructive behavior.