I think having a set of rules or ideas to apply to everyone, but foremost start with taking responsibility for those who live under the governance of those rules makes a whole lot more sense than "screw everyone who is not us".
From my University US history class, this is how my professor described how slavery was allowed by the Constitution: the founding fathers were generally against slavery (at least some of them), but they knew that Americans would never agree to the terms of the Constitution if it included abolishing slavery. From what I understand, the founding fathers decided to just let the system work itself out.
