I don't dispute that and neither does any rational person. The Serbians were killing with abandon and having their way with the Muslim minority.
The question on the table is: Was it in the US national interest to intervene?
Of course that same question could logically be extended to any number of locales.
The Convention on the Prevention and Punishment of the Crime of Genocide, adopted by the United Nations General Assembly December 1948, is one of many rationales for intervention in Serbia.
“Was it in the US national interest to intervene?”
It is in the national interests of the US to stop, when possible crimes against humanity.
I would also add that it is in our national interests to weaken nations that set out as a direct foreign policy, to contradict our national security interests. Clearly, Russia does this. So, if “national interest” is your critical rationale it is about as simple as it gets.
Have your seriously thought this through? Russia, by its adversarial, illegal, and coercive actions is proving it is again, a national security threat.
National security interests? I think you say it but you don’t mean it. The interest is clear. Do you believe that allowing the Russians to rebuild the former Soviet Union Warsaw Pact back into a unified force is in our interests?