Yep, you're right. They've been slowly decoupling services from macOS Server to macOS. A big one is content caching which was added to macOS High Sierra under S

Yep, you're right. They've been slowly decoupling services from macOS Server to macOS. A big one is content caching which was added to macOS High Sierra under System Preferences > Sharing > Content Caching. It will cache iCloud and software updates so that devices checking for updates go though that cache.