I can understand that perspective, although I maintain the usage is only preferred because of familiarity. Since you are already on the fence with ISO8601 I in

I can understand that perspective, although I maintain the usage is only preferred because of familiarity. Since you are already on the fence with ISO8601 I invite you to consider time of day. Would you use second:minute:hour? That is also in (reverse!) “chronological magnitude” order.