Hijab, especially viewed as a set of behaviors instead of a piece of cloth, does prevent rape without a doubt, and not just for the potential victim.
In the West people are trained to think individualistically, and so overlook the broader social impact of cultural practices.

Overall, rape *is* connected to levels of sexual desire, and the more men are exposed to attractive women, the more their sexual desire is stimulated. Some men will seek to express this desire through rape.
So by not observing proper hijab, women share responsibility for rape.

Even if the number of cases where a man sees a woman wearing attractive clothing, is moved by her clothing to rape her, and follows through with it are very rare, such situations do exist.
We need to be careful about minimizing responsibility of either men or women.

Placing excessive blame on men, not just for rape, but for everything, is a staple of Western feminist thought.
This tendency is rooted in the West's tradition of injustice toward women, for which they are now overcompensating by means of injustice toward men.