Destroying public ideals can be a severe cost for societies. When Democrats say "you must vote for genocide because the other side is worse and if you don't you're a horrible person" they are taking a society in which Never Again was normalized and telling people that it always was bullshit.

Once you tell people that being against genocide is a ridiculous purity test and that people have to vote for the lesser evil, people are going to start making some different calculations of what the lesser evil is. What's the lesser evil for them? Why should they care about anyone else?