I have not encountered this strategy in seminars or regular training of Krav Maga. This involved personnel with extensive experience in law enforcement and military training as well as bouncers who actually have been stabbed. Therefore, I would say that it cannot be counted as "relevant strategy" taught in contemporary self-defence as far as my experience goes. The probable reason is that modern self-defence focuses on keeping it simple and using as few reaction patterns as possible for a great variety of applications, ie. the same basic approach to all weapon attacks.
An additional rationale which explains the omission of this particular strategy is the experience that for basically every relevant situation where knives come into play, you simply will not have the time to take your jacket off. It's just not happening that people who want to kill you will take their knives out, shout "I'll kill you" and make circles around you flailing around. Ok, maybe this happens, too, but these are not the people you really have to worry about since they probably are drunk and lack real intent to kill - show-offs and bigmouths, basically.
But the dangerous truth is that if people mean it, you either are stabbed before you even notice it or the attack is immediate the moment you notice that they have a knife in their hands. That is the nature of the reality of knife attacks. Additionally, the common "sewing machine" stabbing from close range makes it very hard to apply such things.
That being said, disarming techniques are not reliable. Everyone who is not delusional and has some real-life experience will admit that. Without breaking bones or at least hits to the body and/or head which disorient or incapacitate the attacker, you will not get that knife out of their hands. It is the centre of their attention and efforts, the focus of their intent. It also does not matter whether the attacker is skilled or unskilled since a knife is more or less a natural instrument when it comes to hurting and killing others, it is a direct extension of the hand.
Therefore, it is all about mitigating damage while going all-out versus your attacker, both physically and psychologically. This is knife-defence. As it basically is the defence strategy against any weapon. It is just harder against knives since they are so elusive and getting hold of them involves serious endangerment like deep cuts or losing a finger or two. So what you learn in modern self-defence are ways to take as little damage as possible while freaking out and hurting the other one under extreme stress levels, as well as awareness and identification of incoming attacks.
Thus, if you have the time and ability to use loose clothing for damage mitigation, it will surely help. But I would not make my bets on that chance, nor should it be the focus and centre of training knife-defence.
