First of all, I think what Pam is talking about is the defensiveness that we too often see in reaction to posts. That is either a self-defense or a misperception of personalizing something not really intended to be personal or something not even directed at the one reacting. Defensiveness is very often motivated by fear - the old fight or flight response...
But more to what you posted, to some extent the "competitive impulse to win" in this context is more often motivated by fear - a self-defensive fear of being shown up, losing, having diminished reputation or standing, being inadequate, or being seen as less than whatever one is competing against. And that is not always a competition against the other person, but can be a competition against ones own self worth, dignity, sense of pride or vanity, values, or whatever. That is very often an element of fear of looking bad, being misunderstood, misrepresented, etc. Saving face by definition is avoiding losing face which also seems to me to be fear driven.
I think there is a fine line of distinction between the person that refuses to enter the fray for fear of losing or being made to look bad or being embarrassed or feeling of inadequacy and the person that stands their ground and decides to fight back to preserve whatever or to win. It again is the fight or flight response. Run away from or hide from the threat or fight to defend against it.