What is gained from empty chamber carry is safety. That's about it. One could argue some bizarre disarm scenario, but that would insincere and unrealistic IMO. I would bet unintentional discharges far outweigh the defensive use of firearms by civilians, so there are a lot of people out there carrying who think they are safe and responsible, but obviously are not. I've known some highly intelligent and well trained individuals who choose to carry C3/empty chamber, so I won't disparage their decision nor do I find their choice to necessarily be wrong or unreasonable.
While it's true attackers will not wait to give you time to better mount a counter-response, there are methods to gain time and distance. Carrying with one in the chamber allows the most immediate and effective reaction, but someone better trained and highly skilled carrying with an empty chamber will likely be more successful in defending themselves than a poorly trained, unskilled individual who is carrying with one in the pipe. With the rather tiny bodyguard and my large hands, I think I just might actually prefer having to rack the slide(gross motor skill) rather than have to disengage that tiny manual safety(requires a degree of dexterity) in a reactive defense scenario. I've seen a several documented cases of well trained folks missing large, ergonomic 1911 safeties during Force-on-Force/FoF drills and a small safety lever on a micro pistol would be much harder to consistently hit. Keep in mind performing any physical task on the range range or during controlled practice environment is much easier than during the chaotic conditions of a real defense scenario or even a dynamic FoF drill.
I have seen this video presented as an illustration of why empty chamber carry is a bad idea, but the problem is she is stabbed in both scenarios. What it reinforces for me is obviously the need not only for situational awareness and early threat recognition, but more importantly the need for unarmed defensive skills and evasive movement(Getting off the X/GOTX) with proper tactics being more important than C1 vs C3.
Her initial response is to try and draw while backpedaling which gains her very little additional time/distance and carries a high risk of falling. A much better option in this specific instance would be dynamic angular movement off the line of attack possibly combined with some sort of deflective unarmed technique. This might gain her the needed time to draw her weapon(and likely rack it if in C3) and get shots on target without getting stabbed at all. Either way, it's a better response than what was presented. I do understand that not everyone is so able bodied, so adjustments must be made or perhaps an entirely different tactic must be employed in such cases.
I'm not saying I recommend carrying with an empty chamber, but many do carry that way and they should understand its limitations and consider the best ways to possibly get around them as well as know it may very well leave them woefully unprepared in certain potential close-quarter situations. I generally carry a revolver, so none of it really applies to me in terms of concealed carry, although I do generally keep my home defense Glocks in C3.