History is not exactly a good judge of how things will work, most history with polytheism is in a certain setting of civilization. Maybe polytheists think their gods should learn to live together, just like humans should.

Also, historically, different monotheisms have waged war too.(but history might be a crappy judge.) The analogy people took with their wars and religion might only be symbolic, and perhaps their actual wars were about other things.

Also, what do you think about seperating beliefs and coexistence into only what that affects one-another, as i stated in previous post.