Something that seems self evident is still worth discussing. There is epistemological good in those exercises. Even if everyone knows the truth, we still need to be able to explain why the truth is the truth. If we punish people for asking questions about the obvious, we regress.

Everyone knows the earth is round. It's been proven. Can you explain why and how? If a flat earther showed you their arguments, do you feel like you could actually explain their errors to them? You came to the right answer but you can't explain your work. Isn't that a problem?

This thread isn't about flat earthers; they're just a good analogy.