This is ridiculous...(question about baby name)?

My sister just had a baby boy. She named him Addison Elijah. Rightful enough considering Addison IS a boys name (meaning son of Adam). And her husbands name is Adam, so it works perfectly. Anways, the both of us grew up with the name being male. But now she is being ridiculed and shamed for giving her son the name Addison. So many people are saying it is a girls name, when in fact it isn't. It doesn't look OR sound feminine at all. I think it is ridiculous how much hate she is getting from people about this issue. When really it shouldn't even be an issue. Anyways my question is.... Why do complete strangers care so much to take the time and ridicule others for giving there children gender-appropriate names???? honestly, why are people so immature and rude?