If you explain why, you give the actual abusers clues as to how to avoid detection. It's common place behaviour for companies to _not_ reveal details.

You can provide a helpful message with options for recourse without giving abuser's "clues." These are not somehow mutually exclusive. By your logic it makes sense to punish a marginal element at the expense of the majority.

It's a spectrum; being opaque and stone-cold to that degree is shitty customer service.