In conflicts between people, groups, or nations, there are many ways to determine who is worse. Morality is a philosophically fraught topic, but we can appeal to common sense notions for the sake of this post. In the real world, it is never the case that each side is literally "just as bad". However, sometimes that's close enough to true to be a worthwhile conclusion.
As time marches on, the nitpicky differences between the actors in a conflict wash out, and we have a removed perspective of who was worse if anybody. Reflecting upon communism and nazism, they were roughly equally dystopian and murderous. For this reason, socialism and fascism can also be put on similar levels of despicability.
Soon, we'll look back on the Republicans and Democrats and think the same thing. Trump was awful, and so was Bernie. The right-wing excesses are harmful, but that's also true of the left-wing. Neither party takes their responsibility seriously, the radical policies they want to implement would probably be disastrous, and they're lying about what they will do anyway.