Django and Plone are very tiny code bases compared with the projects I work with.

- Big consultancy company working with lots for Fortune 500 company groups;

- At least 3 development sites active at any time;

- Some projects can have 100+ active developers across sites;

- Several MB of written source code, plus many modules generated via specific DSLs or code generation tools

- The typical enterprise architectures

- Lots of crappy developers in some of the teams

The implications of static typing helps keeping the possible damages under control.