If I may interject....
Stuhl = chair
Stuhl = stool (as in poop)
Hocker = stool (as in bar stool)
So "Der Stuhl ist klein" could very well mean "The stool (poop) is small", and "should" be an accepted translation. This is what I think Grumpy is getting at.
If that's the case, where "Der Stuhl ist klein" can be translated as "The stool (poop) is small", and that this is what Grumpy is getting at, then I dare say (to Grumpy) that if the German team accepted "The stool is small" (meaning "the poop is small") it would unintentionally teach people that Stuhl = stool (as in bar stool). If this was the first time you came across "Der Stuhl ist klein", and you put in "The stool is small" meaning a bar stool (completely likely as the words are super similar...it would be a common thing to do), and Duo marked it as correct, you'd be learning the wrong definition, and likely use Stuhl incorrectly from that point on.
If I've made any incorrect assumptions here, forgive me.
Yeah, thank you, that's kinda what I was trying to get at. I was thinking of stool and chair as interchangeable, like given the context I think it's obvious I'm not translating Stuhl to mean poop. But now I think I get what you're saying about stool and chair be distinct words. So thank you! :)