It could theoretically help to flag those images. But that kind of submission should be anonymous. It shouldn't ruin the ability for someone to get therapy.

Mandatory reporting makes sense for situations you are connected to. And even then there's presumably good reasons not everyone is a mandatory reporter. This goes way beyond that, mandatory reporting once removed for someone that doesn't know a single person involved.

Hell, reporting someone for that doesn't even guarantee the images get looked into! If they didn't save history they're probably not feeling like going back to the site to demonstrate. Similar if it was sent against their will and they deleted it right away.