I don't think this answer will ever be wrong. Any design sprint, where you have a problem that you are trying to solve will or at least should always start with a pencil and paper. Any tool then is just a way of communicating the ideas that are generated. Also, being able to communicate with senior management who might not care too much about the process of how you got to a solution but just want to see the solution might not be so impressed unless they can see a high fidelity prototype. Similarly, clients want to be wowed and this is another aspect which has to be take into consideration if you spend your time trying to win over clients and build up an agency or if you are a freelancer! But, having said all of that, thanks for the answer.