That's quite the blanket statement. Refactoring is just as much of a problem in statically typechecked languages. I write unit tests for a large C++ codebase and find them incredibly valuable when refactoring. Typically each class has a responsibility. The unit tests verify they are carrying out that responsibility correctly. Acceptance tests validate behavior across multiple units (the hard stuff). I fail to see how unit testing in languages like C++ wastes time. We spend far less time finding and fixing bugs than when we didn't have them.
