Sometimes there is an extremely wrong thing to say in a situation. For example, you probably shouldn’t say “When are you expecting?” to someone unless you were absolutely there when they peed on a stick.
You should also never say, “maybe Trump has some good points” to anyone at any time, any where because lying makes baby Jesus cry.
Similarly you shouldn’t ever respond in discussions around “Me Too” with phrases, “yeah, but not all men” or when you hear someone lament the road that Evangelical Christians have taken with their support of Trump, there is no need to quip that, “not all Christians are into egomaniacal, narcissistic, lying leaders”.
Most likely the people that you are responding to already know that it is not the entirety of the group in question who are like this or that. The only purpose in stating “not all ______” is to make ourselves feel better.