Such a person will disqualify what they are trying to get across just in case it is unacceptable to others.
If it is, then they can claim that they were merely misunderstood.
Listeners would have no way of knowing this, and would be inadvertently led to believe that they were being mistreated by the apparent invalidator. I had a big clue that invalidators may actually be thinking about themselves when they appear to be invalidating others.
One of the ways I learned about borderline family dynamics was when adult patients brought audiotapes of conversations with their parents on the phone when the parents did not know they were being recorded.
It is a process in which individuals communicate to another that the opinions and emotions of the target are invalid, irrational, selfish, uncaring, stupid, most likely insane, and wrong, wrong, wrong.