Or maybe better words which might be used…
Is there any real reason for anyone to believe that someone being accused of something can refute it just by saying “that’s not true” or other WTTE?
I would say that in that case they are merely denying it. Refuting requires some sort of evidence at least, doesn’t it? I mean, it used to mean “to prove to be an error” and you do need to show some evidence for a statement to prove anything.