When a nephew got married in a western state eight summers ago, it was odd that no one under 18 was invited. So our youngest and two cousins, all between 14 and 16 or so, didn’t go. I didn’t go, either, and stayed home with our youngest. I didn’t really care, and it wasn’t my side of the family, anyway.
When couples don’t want young children at their wedding, they should be respected and not bullied into allowing certain children to be allowed to attend (yes, it happens).