What use case do you have for that many displays? I'm sure they exist, I just can't personally imagine needing more than the 3 displays I've got on my desk (my head only turns so far!). Video editors would want a TV as a reference monitor, of course, but not sure how much real estate one person can make use of otherwise.
Multi display video wall, security camera monitoring station, really any sort of monitoring / dashboard station. I use 3 for my main workflow, but could happily drop in some others to put reference material on, etc. If you have a Wacom Cintiq, that's one of your display allotment.