A pre-image is a better proof than a screenshot, still not perfect because it's not only known to the actual sender, but that would be fixed with PTLCs.
Just a better & more reliable version of the 'paid' reply.
Discussion
In a situation you need to know who paid the invoice, but the invoice normally you send directly to a person don’t broadcast to everyone, normally you broadcast a lnurl because you want an “invoice” don’t close after the paid, could be a good adon but I don’t se to be a mandatory feature