I agree with the idea of doing one activity at a time. When I have a lot of things to do, I try to work on everything during the day. At the end, I do not make any progress.
On the other hand, I really liked your expression “Distraction is only one side of the evil”. The Internet is my biggest distraction, especially as you said when I am writing a paper. When I am struggling thinking about what to write. At the end, I waste so much time.