A fist is coming at my face-- what do I do?
The knife is arcing towards my belly-- what do I do?
By looking at this one slice of time, you miss the thousands of better options that surround it. Sure, martial arts are primarily physical skills. In many (I think most) schools, thinking and strategy rarely get more than lip-service. Tactics taught are usually limited to sparring.
Self-defense and survival are very different animals: primarily mental skills, secondarily emotional and only physical when you really screw up or have a very bad, unlucky day.
So you need to look at the problem broadly, in time. This is why situational awareness is so important... but that is another subject that rarely gets more than lip-service. Situational awareness is just a phrase and unless you are taught, specifically, what to be aware of it is an empty phrase. You need to learn violence dynamics from victim selection and terrain to predator tactics. You need to be able to tell a dominance display from a pre-assault indicator and know precisely when a dominance display becomes dangerous. You need to know how the motivations behind an assault differ from those behind a show, because those will dictate effective and ineffective de-escalation.
Broadly. The earlier you can see something coming, the more options you have. The more you know about interpreting what you see, the more precisely you can deal with it. This is, or should be, common sense and it should be integral whenever anyone claims to teach self-defense.
When a predator scans for a likely victim and works to separate her from others, there are stages where she can not be noticed in the scan; stages where she can handle things through social control by remote; where she can make the predator doubt that he has read the situation correctly; stages where she might be able to directly discourage... but if she isn't taught to recognize these or doesn't know what to do, she is left with a desperate fight with a bigger, stronger and possibly armed person who has taken every tactical advantage.
Some do win from there, but very few unscathed.
There is another blindspot that I call the depth of the problem. Things freeze people. They go into denial. "This isn't happening" or they let their identity interfere with their needs, "I know I should fight, but that would be rude." These mental errors have happened too often and been too well documented to safely ignore. The physical aspects of self defense are relatively easy-- or they would be if the mental aspects didn't interfere.
And there is a separate but intertwined emotional aspect: fighting when you are afraid or angry you rarely fight well. An experienced predator with the right victim can shock the victim into a feeling of complete helplessness. It is an incredible act of will and incredibly difficult thing to fight when you are sure there is no hope, no chance. When you know that you have already lost and any resistance will be torturously punished.
Some predators are good at putting people into that mindset. Abusers actively train victims to be afraid to do or try anything... but some few fight and prevail. As I said, an incredible act of will.
If you teach self-defense, be careful not to compress time. Long before the bear hug escape or the snap kick to the knee there was likely a better, surer, safer option. And remember that no matter who you train, in the really dark moment when he or she absolutely needs the skills, they will not be the eager student you know. They will be a chosen victim, possibly already injured, dominated and without a feeling of hope.
Teach them to fight from there.