Good point. I think at some point anonymity needs to be lifted regardless, maybe if the case is strong enough, or if the accusation appears to be fraudulent or in bad faith.
If the accused were guilty, then they'd already know who the victim is and already know who the accuser is, so hiding the accuser does nothing. Hiding the accuser is only ""useful"" when the accused is actually innocent. The entire point of hiding the accuser is to deny the wrongfully accused of the opportunity to defend themselves. Such systems are weapons created by and for bureaucrats to cement their power.
That’s only true if the accused knows the potential accusers and there is a small enough number of potential accusers that it could be reasonably narrowed down.
How are either of those things determined? “Bad faith” seems to be a tool used to dismiss accusations without any objective basis, and determining if a claim is fraudulent may very well depend on the accused being able to rebut a claim based on knowing who the accuser in question is.