Why are some of these charges brought decades later?
If the case isn’t iron clad you’ll have to defend against libel and it gets ugly fast. See for example the case of Evan Rachel Wood or Amber Heard, who had to not only defend herself once, but twice losing once and having her reputation utterly ruined because the one time she lost got so much more media attention.
See also this interview from 2005! Thats 17 years before Weinstein was finally found guilty. www.tmz.com/watch/0-2mpyk0xk/