I think because most people give very short descriptions in their standups i.e. "Working on x today, with a bit of y, no blockers". Perhaps due to things mentioned in the article, people don't want to or feel the need to invite feedback
Having someone leading the standup, if done correctly, can help hold people more accountable for what their progress is toward the sprint goal and remove obstacles. This is one of the responsibilities of a scrum master although you don't need to be a scrum master at all to do this.