Ajax and HTML5 have opened up new possibilities for managing user state.
In particular Web apps now have the option of managing session state on the client side.
This has resulted in a plethora of new stateless application servers like Play Framework
In comparison, WebObjects is at the other end off the spectrum - it can be thought of as a VERY stateful application server.
This is because WebObjects was designed for thin-clients where it's necessary to manage all user state on the server side (via Sessions).