Product development needs consistency
The basic idea of Scrum is to create a safe and change-free environment to enable a team to concentrate on the planned development tasks. The team plans out a sprint of typically two weeks and the idea is that they work uninterrupted during this period. This process really helps to get things done. It avoids the “new == important” trap where everyone thinks that this new idea is much more important than the one they came up with a month ago. Feature development needs consistent priorities to be successful.