There’s a saying in the embroidery community:
“blackwork is done in black thread, except when it’s not.”
This applies to the line between technical documentation and marketing docs as well.
My background is in User Documentation for software applications. In general, User Guides aren’t considered a marketing document. But at one company I worked for, not only did the Sales Guy decide the manual could give better information than a simple white paper or press release, he went so far as to get the manual sold separately as a textbook in a related University class.
Now, not all projects you work on will be University course material! But whenever you are writing, keep in mind the idea that ease of finding information in the manual, whether electronic, or printed, can become a selling point for the entire product. How many times have to tried to set up a VCR or some such piece of technology, only to find that the piece of information you need to complete your task is missing from the docs given to you, and sometimes even from the available online documentation?
Create work that makes people say “Whenever I couldn’t figure something out the answer was just a click (or a page turn) away.” This kind of attention to detail, especially if your documentation includes procedures that can be used as tutorials (even if you create an additional tutorial guide!) can be used by the Marketing Department to show the world how great your product is compared to its competitors. It also goes a long way toward making the Marketing team, the Development team, and the Tech Pubs team look like part of the same company.
And yes, this means that often the technical communicators are not only the bridge between the company and the user, but also between the marketing and development departments of their organizations.
Technical Documentation isn’t marketing writing – except when it is.