How to manage being partial to siblings in certain situations? How does it effect kids psychology?

I came across this article which I think is interesting: http://www.positiveparentingsolutions.com/parenting/kids-fighting This is pertaining to resolving sibling "fights". My main take from the article is for the parent to "stay out of it" and instead, act as the mediator. Encourage or facilitate the process for the siblings to problem solve and come to resolution. I also thought the suggestion of "putting the children in the same boat" as an interesting way to remain partial. Worth a read I think. :)