The total count of human warriors participating in Mahabharata was approximately 3,936,600[0]. Of which less than 10 warriors survive the devastating war. Five Pandavas, Lord Krishna, Ashwatthama, Kripacharya etc.

>Barbarik

The character Barbarik[1] was so powerful that whichever side he chose Pandavas/Kauravas they would grow immensely powerful and it was Barbarik's obligation to fight for the weaker side hence he would keep oscillating between both sides thereby killing everyone except himself. Hence Lord Krishna asks his head in charity and in return Barbarik's head is planted atop a hill overseeing the battle.

After the war, victorious Pandavas were rejoicing and there was banter between regiments of Arjuna and Bheema that their leader was pivotal to victory. When the warriors questioned Lord Krishna who was the "Achilles" of the war, the Lord said why don't you approach Barbarik, he has witnessed the war with a panoramic view. On questioning Barbarik responds,
though for rest of you it might seem that warriors from both sides killed each other, I saw from my vantage point that the Lord's discus (Sudarshan Chakra) killed everyone.
To rid the earth of cruel and unjust kings the war was imperative as per the Lord.

After the war, Lord Krishna visited Gandhari, mother of Duryodhana and Kauravas. Gandhari was devastated on hearing death of her 100 sons, she asked the Lord "O Lord, you are Bhagwan(God), if you wanted, you could you avoided the war and spared my children but you didn't and let annihilation of my children. Just as my family tree has been culled, I curse you O Lord that your clan share the same fate as mine.".

The Lord merely smiled and accepted her curse because after destroying the corrupt warriors, the most powerful family left was his own, the Yadavas or Yadu-Vansh/Yadu-clan. Some time later, the large Yadava family (circa ~millions) gathered for a festival and during merrymaking were heavily intoxicated which lead to eventual fighting in inebriated state and death of entire Yadava-clan except Lord Krishna and Balaram.

>With the above backstory, now we can ponder why did the Lord did not stop the war.

As Gandhari questioned, it was possible for the Lord to avoid war but he did not to teach humanity the savagery of war, brothers killing brothers, uncles their nephews.

>Bhagvata-Gita

The whole of Bhagvata-Gita is instructed by Lord Krishna to Arjuna but Arjuna is merely a medium, every human being is the real focal target. It is instruction on how to lead an ideal life and before death realize the supreme goal of life i.e. moksha/salvation/one-ness with the Lord.

Had the Lord avoided the war we would not have Mahabharata war as example of annihilation of 3.9m warriors.Back to the present age, it took us three colossal World Wars to learn this ancient lesson. Clearly us humans need to be reminded of our lessons repeatedly.

You are correct on Dharma-Yuddha not translating to "holy war", it was my attempt to simplify the idea to western audience.

>On Hindu representation in western media:

Personally, though I am a practicing Hindu, I believe in the concept of "universality" of ancient Hindu tradition and its modern counterpart from the scientist Carl Sagan[2]

“The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.”

All of us trace our origin to stars and yet we pigeonhole ourselves into Hindu/Muslim or While/Black. If we are the same at the core and only superficially different why waste precious breaths over petty differences.

Ending with another Carl Sagan quote:

“Every one of us is, in the cosmic perspective, precious. If a human disagrees with you, let him live. In a hundred billion galaxies, you will not find another.”

[0]https://en.wikipedia.org/wiki/Akshauhini

[1]https://en.wikipedia.org/wiki/Khatushyam

[2]https://www.goodreads.com/work/quotes/3237312-cosmos