Good gracious! Why do y'all keep saying "able-bodied children"? It's not like the OP is saying she wants to put them in a wheelchair. Strollers are not intended for non "able-bodied" children.
Even a pediatrician will tell you that a full day, walking, at Disney can be too much on a child. It's not "a little exercise", it's MILES and hours of standing still.
We make the distinction because if, on the Dis, you ever suggest that something might not be age-appropriate, the immediate response is someone saying, "but my special needs/ disabled kid..."
So yes. There are exceptions. A 10 year old with low muscle tone is not the same as a 10 year old with no physical problems or disabilities for the purposes of a stroller discussion.
My pediatrician looked at me like I had two heads when I asked her what she thought of putting a big kid in a stroller for a day at Disney. (I was curious, since nowhere but the Dis have I ever heard of 8 year olds in strollers. Wanted to know if it was just me.)