According to https://stackoverflow.com/a/5039371/769384, which clearly states the difference between servlet containers and app servers, it seems that a web container such as Tomcat should not be widely used in enterprise applications.
Lots of libraries would have to be installed additionally, so it's a lot easier to install an app server that provides it.
The question is - do I get it right? Are there any enterprise applications run on tomcat? What would be the benefit of deploying a Java EE (EJB+JPA+JSF+...) on a Tomcat instead of a GlassFish server?
Servlet containers which can be also called web containers don't support EJBs', they only support Servlets and JSPs' along with other related technologies.
If you need to deploy and EJB, you'll then need an application server.