Oat milk is a milk substitute without the nutrition of milk. It contains antinutrients like seed oils (canola oil, etc). Plus all kinds of extra chemicals, to give it a similar texture. It has almost no protein. Milk is one of the most nutritious foods around.

Why would you drink oat milk? There's lots of things that have been engineered by food scientists to stimulate our taste buds, but are long-term harmful.

This is coming from the perspective of someone who's been carnivore for about 3 months. But even before that, I tried hard to avoid highly processed "new" foods, that our grandparents would have ever heard of.