Many people, when they say 'culture' in the context of kids, mean something that kids can discuss around a lunch table. If OP's kids don't watch youtube, they won't have this particular aspect of culture as an inroad to make friends.
Like other humans, kids don't have universally aligned interest in media. Also, "missing out" can be good in many cases, depending on the content of said media.
Sure, but if YouTube makes up say 20% of culture, that's 20% of conversations they cannot participate in. I'd love to read any source that says that "missing out" on making friends is actually a good thing.
