In my experience a horn is far superior to a voice. For one, it's much louder. And as rude as a horn might seem to some, I've had much worse experience from shouting at drivers. It doesn't matter how polite you try to be. The volume of your voice is going to make you seem like a jerk. In contrast, most drivers respond fine to my air horn.

I agree that horns can be rude and disruptive, and perhaps most honks are. But I stand by every time I've used mine. I don't use it frivolously. Whereas drivers seem to use their horns frequently because they are impatient, I use it only because I'm in danger.