Don't require users to login to their first session
The designs for the first run experience propose that users shouldn't have to login to their first session. Instead, once initial setup has been completed, they should be immediately launched into the session. This obviously reduces the amount of work for users, and makes the first session feel a lot smoother.
I think we used to do this at some point in the past, but subsequently regressed. This issue was previously reported here: https://bugzilla.gnome.org/show_bug.cgi?id=763247 (March 2016). I experienced it yesterday testing 3.28 with Fedora 28.