Liberals and leftists believe themselves to be both intellectually and morally superior to their opponents and it costs them votes. People don't want to talk politics because they know the Libs are going to try to shame them or insult them so they just don't talk politics. As a result the Democrats don't realize they can no longer communicate with large swaths of the population.  

 
The Republicans used moral arguments to defend their stances on abortion and gay rights, framing them as right vs. wrong. It is wrong and immoral to get an abortion, it is wrong and immoral to be gay etc. In the 2000's the Democrats countered this by reframing the moral argument as a civil rights issue. It is wrong to try and control someone else who has a right to live their own life. They had a lot of success. However, they extended this strategy to almost everything. Healthcare is a human right etc., and they increasingly started viewing almost issue as a black/white and right/wrong and have boxed themselves into corners. They can't see that issues are not black and white. They don't understand that the world we lived in before 2020 is gone and not coming back. They have created bubble so thick they can't understand other people anymore.

Pearl Harbor, 9/11, and the sinking of the Titanic were all historic.