Here, Slack, Miller, & Doak describe the role of technical communicators as the transmitters of messages, not authors. However, as this was stated in 1993, I believe that the role of technical communicators has evolved over time. In "Wicked Problems in Technical Communication," Wickman discusses the role of technical communication in solving "wicked problems." In Sullivan's "Beyond a Narrow Conception of Usability Testing," she argues that technical communicators have a distinct role in promoting increased product usability. In both articles, a major theme is that the technical communicator is an individual curator with a unique set of ideals and goals, which proves that technical communicators are seen as authors more than ever before. To get a better understanding of the role of technical communicators as authors, refer to this infographic:
http://stuffwriterslike.com/wp-content/uploads/2014/09/future-of-technical-writing.png
Sullivan, Patricia (1989). Beyond a Narrow Conception of Usability Testing. IEEE Transactions on Professional Communication 32(4).
Wickman, C. (2014). Wicked Problems in Technical Communication. Journal Of Technical Writing & Communication, 44(1), 23-42.