It's true that "both sides are bad" is what led us to being closer to fascism than ever.
But you've got it backwards.
The "less bad" party being able to count on securing votes simply by being "less bad" allows for the "more bad" party to lead the march, and the "less bad" party to follow while still being "less bad". This creates a slow march towards fascism while maintaining the illusion of choice in the population instilling passivity as they can always just "vote for less bad".