If the dude has a knife, you don't wanna wrestle him. Or box him. If you don't have a weapon longer than that knife, or you don't have a gun, you best leave the scene as quick as you can. Chances are good you can bleed out.
NO style, or system of anything will protect you if it's your time no matter how hard you train or how good you are in the safe environment of training.
The argument is and always has been moot. Tussling, rolling, sparring, competitive boxing isn't balls out fighting. It never has been and I can point to a few examples of primo fighters being shot to death, stabbed etc in what should have been a minor altercation.
What you train, where you train and if you compete has no bearing on the reality of true violence. But, I would say that training is better than not training for me personally. Psychologically I like to believe I have an edge even when I know I don't really.