The claim is almost always made when someone is trying to make an argument against another. It is intended not to extend the debate, but to cut if off, by charging malfeasance.
The suggestion that a Christian would never ever say anything negative about another person is belied by scripture in which we see Jesus doing things that, if done in a forum, would cause opponents to say He was “turning off people” who would otherwise believe in Him.
Like calling the Pharasees vipers, and saying they were leading people to Hell — hardly something that would make the Pharasees see the error of their ways and turn back to God. Or maybe it would, and Jesus just knows a little bit more about human nature than anonymous posters to the internet.
You are twisting the facts. Jesus spoke the truth and never engaged in false witnessing as we see here. Jesus never distorted the other's position for his personal gain as you do.