Why Whitehorse designers are not using UML

Today I read Keith Short's why Whitehorse is not using UML?  In it he describes why the Whitehorse designers use DSL's (Domain Specific Languages) rather than UML.

Whitehorse includes the Distributed Service Designer, the Logical Infrastructure Designer and the Class Designer.  MSDN Subscribers can try the Class Designer in the Visual Studio 2005 Technology Preview available for subscriber download.  Create a J# project and use add item to add the Class Designer diagram.