Why do feminists think that the lifestyle of one who alleges should not be taken into consideration?

Given that Kobe Bryant and the Duke Lacross teams were shown to be not guilty of the accusations in large part because the alleged victim had been with multiple partners on the dates in question, and given that civil litigation (which now frequently accompanies legal prosecution) can provide women with a very lucrative motive to manufacture allegations, why should a woman's prior record of promiscuity not lend itself to such a case? Many character traits are considered admissable in court that can aid the jury in determining who may be telling the truth, so why not promiscuity (which is highly relevant in a case)? Do feminists believe that women should simply be permitted to raid the coffers of wealthy men without extensively considering the truth behind the allegations?