The problem is that an architecture is created that does not fit the problems that need to be solved. This is inevitable if lots of architecture is created befo

The problem is that an architecture is created that does not fit the problems that need to be solved. This is inevitable if lots of architecture is created before working on real requirements. TDD gets this right: start with actual requirements and extract an architecture from the resulting code so the architecture will actually apply to what is desired. Software is so flexible that that everything can be written in millions of ways. But there are also billions of ways that cause more problems then they solve. You have no chance of selecting one of the millions of working ways out of the billions of wrong ways by starting out with architecture. The numbers are just too much stacked against it.