Also, I think Wrapping alone is not enough because the receiver can always unwarp and simply re-broadcast the wrapped event. The one we did forces another Seal event of an unsigned event.

The Wrap has the receiver. The Seal is signed by the sender. But only when both are open, you can see the contents.

The Wrap without a Seal means the receiver can either expose the inner event if signed OR, if you don't sign the inner event, the receiver will not be able to verify who the sender is.

Seals alone are signed by the sender, but don't have a destination or any other ptags. So, they are not that useful by themselves.