Touche’, I’m sure your characterisation would appeal to the hand-wringers but, for want of a better word, it’s simplistic. Most people freeze or panic when faced with a threat. By being unprepared to react immediately and decisively they relinquish control over their fate, and possibly the fate of their loved ones, to the (as yet undetermined) whims of a stranger.
Reaction is not vigilantism – it is self-preservation. “In the moment” the only thing you know for sure is that someone is trying to commit a crime against you, with the exact nature and extent of the “threat” impossible to know accurately. It may just be a “petty street crime” but if you assume that and you’re wrong you may well have missed your best (only?) opportunity to manage (control) the situation.
There’s no time to ask yourself “How many are there, do they have weapons etc.”? Anyone who tries to decide what their “proportionate response” should be under such circumstances is naïve to what can happen in the real world, especially if that real world is a foreign city and you and your wife are alone against multiple offenders in an underground metro.
Everyone should give some thought, ahead of time, as to how they could or should react in a threatening scenario. I’m definitely not paranoid but I am pragmatic - to me that’s just common sense. Be alert, not alarmed, as they say! The time to give it some thought is not when something is actually happening. Even if there don’t seem to be any options you still have to think of one.
The strategy I was taught was to enlist the element of surprise and a greatly disproportionate (excessive) response to neutralise the situation in as short a time as possible. If confronting more than one person the imperative is to ensure you only turn your attention to the next one once you know the first has been rendered incapable of further participation. That means being efficient – and if you know your anatomy and have good technique it can be done safely. Edit: Doesn't help when you skin your knees scrambling up the stairs after No. 2 though!