I too see how on paper it doesn't seem to change anything, but I think culturally it's a huge gap. The incentives are not always to bill the most, and you also

I too see how on paper it doesn't seem to change anything, but I think culturally it's a huge gap. The incentives are not always to bill the most, and you also might have to pitch a time estimate before starting the task. Having a day as the minimum unit removes the need to decide if it's a 2h fix or a 5h fix, an estimate that could take 2h in itself to reach. Then a lot of scrum team will report advancement daily, and it will be way easier to communicate with the client with a billing that fits that cycle (this is also where you probably don't want to report small time sliced increments to the client, if they're already not very happy with your 20 days estimate for changing a page's footer)