That leads to focusing on the nitty gritty details first, building a library of thing you think you might need and you forget to think about the whole solution.

If you come up with another solution half way through, you will probably throw away half of the code you already built.

I see TDD as going depth first whereas I prefer to go breadth first. Try out a solution and skip the details (by mocking or assuming things). Once you have settled on the right solution you can fill in the details.