I would argue TDD is a workaround which allows you to do meaningful work in a team context without holding a complete program in one's head.
It gets everyone to put their thoughts about what the program should do in one place. Every time you run the test suite, you are outsourcing to the test suite the task of running through your mental model of the program and thinking "what did I break".
The limitation of TDD is that it blocks rapid iteration in what the program should do. When you load the entire model of the program into your head, requirements change at the speed of thought. With TDD, they change at the speed of a lot of reading and typing.
It gets everyone to put their thoughts about what the program should do in one place. Every time you run the test suite, you are outsourcing to the test suite the task of running through your mental model of the program and thinking "what did I break".
The limitation of TDD is that it blocks rapid iteration in what the program should do. When you load the entire model of the program into your head, requirements change at the speed of thought. With TDD, they change at the speed of a lot of reading and typing.