Defense training is confusing. The whole idea is counter-intuitive
to me too. One would think it would easily create a fear biter.
It does bring out the fight drive because it removes flight.
I think old school protection training employed more of this and now
prey drive is used more often to train, at least in earlier stages of protection than once was the case. But at higher levels, pressure applied to insure the dog won't disengage is essentially still in use.
On the other hand, if a dog brings fight with confidence, then
mission accomplished, quickly. Sort of depends on the dog, it's drives, it's maturity.
Not unlike the old school OB by enforcement versus positive methods,
protection training has too employed more prey drive to shape behaviors in protection training. You might get there quicker successfully with a harder critter, but you may shut a newbie or softer one right down, which is a huge set back.
And of course, you would never even attempt it with a fearful one,
that's what temperament testing beforehand will wash out. Not all
can bring it, especially when immature.
I'm sure others here can speak to it better than I, but there's a time and a place for all things...and it seems to me from what I've come to understand, working in defense happens less often than it once did, and later in the whole process than it used to. Folks who've been at it a long time can tell you better than I can...but I had the same doubts and walked away from it nearly 40 years ago, and again just
8 years ago after witnessing an "old schooler". But now, am enjoying
it using a more measured approach.
Hope this helps.