By your logic, we shouldn't arrest murderers? Even if they're caught on video, it could be a deepfake. It all comes down to people testifying something is real. it always comes down to convincing a jury or a judge that the defendant is guilty.
This is a common pattern I'm seeing in recent discussions. There is a practical problem, so instead of fixing the problem, let's not use the system entirely. Perhaps for victimless crimes I would agree with you, but it is not for you or I but for the victims or whoever is survived by them to relinquish their demand for justice.
For serious crimes, suspicion must be corroborated by evidence. hear-say, accusations or eye-witness testimony alone can't be used to even begin a trial.