[WesolyKubeczek]

I prefer this response:

> X wasn't really designed/is not very suitable to do Y. Why did you resort to do Y with X?

It opens a lot more possibilities and doesn't sound too hostile. Maybe you get to learn that Z which is made to do Y is broken. Maybe a part of that person's workflow requires X specifically. One can learn a lot of things this way.

Consider a person asking about using some surgical equipment on themselves (though they likely wouldn't ask it on StackExchange). Normally, you shouldn't perform surgeries on yourself, but what if you're stranded in Antarctica during the winter night and your life depends on it?