You can't count on martial arts to keep you safe, especially as a woman. It will help against aggressors who're more cautious, but against determined attackers, you need a significant amount of skill if you're not stronger.
You can definitely count on martial arts to keep yourself safe. Or actually, more accurately, to
try to keep yourself
safer.
The way you put it is like saying you can't count on workplace safety to keep yourself safe because there could be accidents that will still manage to affect you.
Or, you can't count on helmets because it may work for small impacts but not when a truck runs over you.
Point being, it's uncalled for as it sounds as if it's discrediting the use of it, and it is common or obvious sense anyways that it only serves protection
to an extent just like anything else, to prevent things that would've been more avoidable, but it's there to
increase the likelihood of personal safety. Either you be an easier, weaker prey, or be able the repel danger and have a higher chance against more capable attackers.