I believe this misses the point. We have significant influence over almost everything that happens to us. For example, when a deal goes sour both parties could most likely have prevented it. Important - this does mean we live in a hopelessly relativistic world, and leaves ample room for clear convictions about who did what wrong.

The point is that even if the other party acted a lot more 'wrong' than I did, it is still surprisingly often true that I could have completely prevented it. Furthermore, I am significantly more responsible for avoiding damage to me than someone else is. Once you realize that, an attitude of 'everything is my fault' naturally follows, and I applaud it.

EDIT: slightly shortened