Agile reverses the trend of isolation of disciplines. This trend sees designers turning more to long-term plans and documentation to communicate with teams that are ever increasing in size. Scrum practices require the designers to collaborate and communicate face-to-face on small, cross-discipline teams.
In reversing this trend, designers need to embrace the benefit of emergent design. No designer has a crystal ball about any mechanic. The limitations of what is possible prevent this. Instead, they need to ensure that their vision is communicated and open to all potential ideas.