Another angle is that in software development, it's pretty common to have days where there isn't much material progress but things are getting better understood

Another angle is that in software development, it's pretty common to have days where there isn't much material progress but things are getting better understood by the developer themselves. Senior engineers in my experience are quite comfortable doing several days or even weeks of scoping, investigating, prototyping, and general maneuvering before coming to a solution that ends up taking a day or less. The constant need to interject with help when "no progress" flags are thrown gets into the realm of micromanagement, and that is doubly so when every day or even hour of "no progress" gets treated as a crisis that needs to be solved ASAP. Scrum fosters an environment of "no breathing room" for these frequent and common stretches of "no progress".