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.
Understanding any problem is a crucial condition for solving it. That includes accurately understanding and characterizing what's going on. The goal isn't to name-call people sucked into a fascist movement, it's to not bury our heads in the sand and pretend fascism isn't making a huge comeback. That includes actually being able to explain to these people the nature and structure of a fascist movement so they can understand how they've been duped.