Wiki - The paradox of tolerance states that if a society is tolerant without limit, its ability to be tolerant is eventually ceased or destroyed by the intolerant. Karl Popper described it as the seemingly self-contradictory idea that in order to maintain a tolerant society, the society must retain the right to be intolerant of intolerance.
Fully agree. The only catch with this is it can be distorted with propaganda to point to anyone as being intolerant, with enough saturation. The bar for recognizing intolerance needs to be fairly high.
Why?
We don't want to risk further radicalizing those still within reach and not completely indoctrinated.
We don't want to risk a false accusation and provoke witch-hunts.
We don't want the intolerant to use this against the tolerant.
It's why I'm always a bit leery of the knee-jerk punch-a-nazi movements.
I've personally witnessed my little brother express hating the left more than Nazis after he was banned from a video game for calling someone a retard.