They’d have to report it themselves. This is a worse value proposition than regular blackmail, where you take an existing violation, which the target already kn

They’d have to report it themselves. This is a worse value proposition than regular blackmail, where you take an existing violation, which the target already knows is illegal and has already shown willingness to conceal from authorities (or is not illegal at all, but e.g. just embarrassing), and threaten leaking it. In the proposed scheme, the mere reception of the threat itself creates a new situation for the receiver which must be reported. Paying off the blackmailer puts you in a worse spot than before. Not so with “ordinary”, Hollywood movie blackmail.