I don’t know how it works in the US, and it’s certainly not perfect, but if you bring “compromised” evidences of actual child abuse, you can be sure it’ll trigger some extensive investigation. Sometimes, this leads to nothing. Sometimes, the “evidences” were not really evidence, but more of a hunch. Sometimes, it leads to actual consequences.

One issue with such a vigilante system is that sometimes, you’re wrong. That’s why due process is a thing. But the “this evidence was collected illegally, so we won’t even look up the guy” thing isn’t really a thing, as long as the evidence is better than “I’m sure of it”.