The idea of the multi user time machine type of share is to automatically create a dataset for each user when they use the share for the first time.
That’s what my TN CORE does, at least, and what I expected. The home directories of the users are on another dataset, not identical with the TM share. Which I also would consider best practice - users can login via SSH to use the system for shell “things” in our organisation, therefore they need a home directory to save their “stuff”. TM backups are a different thing.