A member from those men who are trying to rape a girl or a woman might change his opinion after he see the suffer of the woman or the girl and might convince the rest of the group who did not rape of this wrong act.
In the Article it was mintioned that the Sharia law requires 4 witnesses, why?
Because the Sharia law try protect the family connection to the extreme, see Thelonius in Western or Arabic countries many families got shattered because of roumers that the husband (good father) had an affair or the wife (good mother) had an affair, and then the children will suffer of staying without a father or a mother, therefore there must be 4 witness to prove that the wife or husband is guilty.