Yeah, it would be great if we get some specific example, or reason, but I can also see it from the perspective of the person attacked not really wanting to share anything anymore. The "bad experience" could range from "someone was slightly mean to me" to "I get death threats and dick picks in every reply"...

So it's a balance and I'm not sure "I wanna proofs about your claims" is the best strategy to achieve your end goal. There could be a more effective reply to get you the result. 

 I'm asking for a proof exactly because i didn't see anything blatant about her claim