I would not use the term or call people "ignorant" or call them out over their "ignorance". It is a demeaning term which will raise the heckles of anyone. It challenges a persons knowledge, that they know nothing about the subject or opinion being discussed.
Helping a person or the group involved to understand a point of view or pointing out or adding to the discussion, adding to the threads knowledge would be a better and more constructive way of making the thread less challenging.
We are all here to learn and we accept constructive discussion, rather than being pontificated upon.
I like to share my knowledge, but am grateful for others to share their experiences. But I wouldn't call contributors "ignorant", unless it was plainly obvious. I have a little more respect than that.