Some clients want us to write from scratch. Some want us to just rewrite what their employees have drafted. When we perform those services, the purpose is not to teach (although employees can learn something from comparing the finished product with the original and by asking questions about what we've done).
But for certain companies that want to invest time and money in improving the skills of people who do a lot of writing as an integral part of their jobs—companies like marketing firms and public relations agencies whose main business is the communication of ideas—we offer more than rewrites.