It can cause bloating
Not everyone has this problem, but the lactose intolerant among us know exactly what dairy-related bloating feels like. The inability to process dairy efficiently is a painful problem, and even a teaspoon of half-and-half in coffee can lead to a miserable day. Though humans by and large have evolved to tolerate dairy even in adulthood, we are the only species that does this, as well as the only species to drink the milk of another animal. So perhaps the lactose intolerant are the more “normal” ones.