For people who wonder why saying "X isn't all bad" (ie. "Not all Cops" or "Not all Men") is an issue, maybe this will help.
Let's say you live in a neighborhood and there is a fire. Several houses are on fire, but not all of them. The firefighters come and start spraying down all the houses, on fire or not. Some people whose houses are not on fire are very adamant about getting an equal spray down for their houses, even as the ones on fire aren’t getting enough water to slow the infernos. This seems silly, right?
The houses that need the water are ON FIRE, the others aren't benefiting from it and might actually be being harmed (water damage). In addition since the firefighters are not all focusing on the houses on fire, the fire could grow and spread and take out the entire neighborhood. Obviously the people whose houses are actively burning down are going to be upset in this situation. After all, it's their houses burning down, but it isn't just an issue just for the houses that are on fire either though. No matter how you look at it the entire neighborhood is at risk if the fires in those particular houses that are actually on fire aren't put out quickly, efficiently, and permanently.
Basically by saying "X isn't all bad" you are being the firefighter shooting water at a house that isn't on fire or, if you are being completely insensitive, one of the short-sighted and selfish home owners who insists on their house being sprayed even though it isn’t on fire. You are turning the focus away from the very obvious issue (houses are on fire). In addition you are actively harming the X's that aren't doing the bad things by making it seem like the innocent X's are against addressing the issue and dealing with the non-innocent X's obvious problems. Yes, not all "X’s" are generally never ALL bad, although exceptions to rules always exist. Generalizations are generalizations after all. However when specific houses are on fire it really doesn't matter that others aren't, you know? Everything could end up burning down if you don't actively work together to solve the problem while it is still manageable.
