I've heard that "opposites attract" my whole life. The magnetism of people that are different creates a bond that can't be broken. People that are in relationships like this typically repeat the cyclical pattern of fighting, making up, fighting, making up until they break up.
I think it's a waste of time, and the biggest reason for this misconception is that most folks are ignoring one simple truth- you can be with someone who is different from you in many ways, as long as you still compliment each other.