* Edit
This thread was originally titled simply "Reckless accusations of trolling."
* End edit
One of many things that might make people feel unwelcome, including other people who see it happening, even if they are not targeted.
I imagine it would do nothing but harm to try to stop people from doing it.
My suggestion is not to respond to it at all, even to dispute it. In my own experience, when I've been maligned in forums, seeing people arguing with my detractors did not help me at all. In fact it made me feel even more alone. What helped me was friendly responses to my posts.
ETA: Other ideas about how to respond are welcome here.