I do that with my DS and he's the eldest (and only). Doesn't sound harsh to me!

From seeing other parents through my entire life, the youngest always gets their own way and the eldest is expected to shoulder more responsibilty because they "should know better" - irrespective of the fact the younger child should have known better for years! (Bitter oldest child side coming out!)

But I have seen the oldest child having chores from age 7... fast forward 7 years, the oldest child is expected to do chores but the youngest, now 10, doesn't lift a finger still.