yes, if all of those circumstances are true, then it would be unfair to the accused (and should be punished accordingly).

however, it seems to me that journalists are being unusually careful about reporting these abuse allegations because of the exact pitfall you point out. some of the reports cite tens of sources (some named and some unnamed), so they're trying to play it safe when it comes to the reporting.

that's not to say that journalalists are infallible, but that they are taking precautions not to potentially destroy careers based on rumors alone.