Because everyone has principles. If we stand by our principles, no one can fault us. Plus most principles are basic and are shared by all… laws may be biased, loyalty may be unfair, love may be blind. But with principles, everyone can see where you stand.
Even in politics, taking sides serves no purpose, because one day you have to be on this side, the next, you have to be on that side, where does it end? Should we not be friends and at peace with all by standing by our principles? After all, everyone understands and will support the act of doing just and doing good. Would we finally have peace around the world?