I think that realization is the very opposite of the "Not all men" mindset. Saying "Not all men are like that" is a red herring - it's a way of distracting yourself from the fact that there are people out there who treat women like dirt by saying you don't do that.
I think where we're failing as a society is the inability to close the loop and turn "not all men" into "yo dude, not cool" - we don't seem to be very good at getting men to call out sexism in other men.
I would love some kind of resource for how to do that effectively.