Why is “not all Black people” considered a valid argument, but “not all men” is not?

When someone says, “Black people need to stop committing crimes,” and someone responds with, “Not all Black people,” the reply is often dismissed with, “Maybe not all, but too many—Black people, in general, commit more crimes than any other race.” This is immediately condemned as racist.

However, when someone says, “Men need to stop committing violence against women,” and someone responds with, “Not all men,” the reply is often, “Maybe not all, but too many—men commit more violent crimes than women.” Instead of being condemned, this is widely praised as a strong feminist argument.

Why is one considered unacceptable while the other is widely accepted?
Why is “not all Black people” considered a valid argument, but “not all men” is not?
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