I already explained...
Anarchists hate *any* government, including democratic ones. Thus, when the fascists attack democracy, the anarchists will just shrug, and won't lift a finger to save it. Maybe even jiggle, "that is what those corrupt tyrants deserved".
That is why fascists welcome the spread of anarchism. And they know that anarchists will never be a threat to them, because, by definition, anarchists can't mount an organized resistance.
Isn't that so?