@Necrokora because it's a known technique that works irl.
At least in Japan (and I suppose some other Asian country) being accused of rape/molesting can get you in big trouble, whether the claim being true or false.
It's fast, easy to do and doesn't hurt the person who claim being molested.
Of course there can be punishment if the claim is proven wrong, but it takes time, can be biased and can still ruin the life of the true victim.
PS : this DOESN'T mean that all rape accusations are false or that we should not trust people who claim being raped.
Rape is to be taken seriously. For both side. Early judgments (which include mob judgments) should be avoided in these type of cases. But most of the time they aren't; which create really sad situations (for both sides).