@Hey_Beth The difficulty here is that having the party better vet candidates won't result in them focusing on things like sexual assault, but rather on keeping out people who advocate things big donors to the party don't like. So ideally it should be the media, not the party, that tracks down and exposes troublesome people early enough for it to matter.

Platner survived as long as he did because many of his accusers clearly had other motives, like AIPAC or Republican connections, which allowed his supporters to plug their ears. Also, people wanted a fighter, not a writer of strongly worded letters, which might have made a problematic macho dude seem attractive.