ANAHEIM, Calif. — Without as many traditional Internet A-listers as years past, VidCon, an annual social media conference for creators and their fans, seemed unusually quieter this year. That is, ...

Ollie was asleep at three in the morning when the Discord app on his phone started blowing up. He panicked; many of his friends lived in different time zones, but they knew how late it was for him.

The Dream SMP, a private server for Minecraft content creators, has exploded in popularity. Hundreds of thousands of fans watch videos about lore and characters in the server's expanding universe. Fan ...