Using time instead of points breaks the whole concept of sprint-based estimation which Scrum tries so very hard to defend. Basically Scrum claims that software

Using time instead of points breaks the whole concept of sprint-based estimation which Scrum tries so very hard to defend. Basically Scrum claims that software developers can't estimate based on time so it forces them to use an abstract number instead. Over time this would lead to being able to estimate a project in sprint-sized blocks. This is why sprints have a fixed duration, the sprint backlog should not be changed, stories are awarded the full points or 0 during review, commitments to finish the sprint, etc.