Not a buyer who won't use it. Design for one user only. May include some negative personas that we are not designing for. There are also corporate goals. Tasks are not goals, they lead to goals.
Tasks depend on technology but goals stay the same.
Goals may involve many tasks but the tasks must not disguise or block their goal. Let user achieve practical goals without violating personal goals. See motivation theory. Act them out to test a design. Play the part of the specific user, not the computer.