In Features Workflow and Master Features Workflow, exclude users who are not assigned to any features or master features. This also would apply to the "Assigned to User" filter when it is added to the workflow board; exclude all users who have not been assigned. Including users who will never have anything to show just clutters the page and causes distraction and extra work.
Thank you for the idea. Currently you can filter out users by clicking Configure Board and deselecting users who should not be shown in the board. The users who should show in the board but don't have anything assigned to them are still shown to help you easily see who has capacity to take on new work.
Based on the option to hide users outlined above we are unlikely to implement this idea at this time.