Adult names for babies

I understand years back when the names were popular. But what would possess a person to look a baby dead in the face and give it a serious and adult (non-generational) name. Like how do you see a newborn and be like ‘This is Phillip.’ I know this is irrational and the baby will grow into it once they reach adulthood but it is just beyond my understanding. This doesn’t apply to cultural or passed down names it’s just more about people who pick such a grown up name out of thin air and decide to go with it.