It's time to pass some laws that punish false sex crimes accusers with the same crime that they are accusing someone of. If you are found to have made false accusations of rape, then you are charged with rape, and when convicted receive the exact same punishment as an actual rapist, including being placed on the sex offender registry.
Defamation is a civil thing and only a monatary judgement can be won. With rich political backers that is not really a punishment at all. That is why it needs to be criminalized and handled by the criminal courts.
If this is not done, then people will continue to use this as a political tool, which is absolutely disgusting, as well as harmful to actual victims.