But if we really can't attribute blame to specific individuals, your proposal is effectively collective punishment where individuals that are genuinely innocent are punished because of wrongdoings of other members of the group. From a justice perspective, we're in murky moral waters. An analogy would be to punish everyone in a shared household if we know that one member of that household committed a crime but we can't determine which one specifically (and let's assume that the innocent members of the household don't know and aren't hiding information). This would be a state of affairs that everyone would rightly protest. So we need to think carefully as to whether we want to enact your proposal.