I have been lucky so far and have not met a "witcher" yet. Is it mainly a normal rather than hardcore game thing? I only play hardcore TDM along with S&D which may explain it. I have however met the stupid care package glitch a lot recently. One time in particular playing Sub Base on S&D just took the pee as there was no counter for it.
You won't see the witch class on hardcore simply because they won't get close to you use to use it.One shot and they'll be dead.Whereas in normal even if you empty a few rounds into them they could still kill you with it.