My understanding of the classroom feature is that it’s built around a classroom usage model: Hand out clean iPads in the morning, students sign in, collect them in the afternoon, wipe, repeat.

It’s not designed for fast (enough) switching or maintaining “hot” data from multiple users simultaneously on the same iPad.

It's apparently not as fully functional as you'd expect. It's designed where apps will have their data all stored in the cloud and profiles act as just a single sign on where the apps will sync down the correct data depending on the signed in user. Especially important as users will be switching around between physical devices so it all has to be cloud storage anyway.