The same thing could be said about police qualifications.
This kind of discussion can go round and round! And does.
We all have opinions, mine is based on teaching for 25 years! People who go armed at work, ATM/Armored car/Police/Tactical units/and Instructors of those groups.
And in the area of reacting to danger, instantly! I spent 5 years as a Doorman (Bouncer) in Clubs in Liverpool UK, 4 years at the Cavern of Beatle fame 1960 to 64, and year 1965, at the Blue Angel, on Seal Street.
In those years we fought long hard and often! Getting stabbed twice smartened me up as well! Of the men I worked with probably around ten or fifteen over the 5 years, three where violent instant reaction individuals, basically nut cases, George, Larry, and me!
Instant aggression seems to me to be a gift, not able to be taught, improvements yes, but the one of a kind instant attack, person?
No thats a gift.