Yep I grew up on milk, I would easily dump a gallon a day in 24-30 hours for years on end and I honestly wonder if that caused me to become insulin resistant. I used to be thin when I was younger, and now I have to eat clean just to see anything under 13%, and I dont eat highly dirty like a lot of people do who eat out every night or even a couple times a week.
So hey, I love milk and kids cereal and pizza and burgers, but I'm not dying to put on weight that is going to take anything away from my overall health. Its not hard to eat 3000 or 4000 calories clean, and most people wont need more than that to see a sustainable bodyweight that is agreeable with their genetics.
We may look at milk as cheap protein and calories, but can your body even really use the protein effectively? Again, it is all debated still to this day. I can live without it.