I don't think it's only a matter of partisans being louder, it's that partisanship is easier. Seeing only one side of an issue is always easier, in the same way

I don't think it's only a matter of partisans being louder, it's that partisanship is easier. Seeing only one side of an issue is always easier, in the same way that empathizing with only one of two (or more) sides of a dispute is much easier.