If you aren't making a consumer product for nursing home patients with sub-90 IQs, then you'd be wasting your time, and the feedback you got from the exercise wouldn't be useful. In fact, any decisions you made based on it could be wrong. The point isn't to design for the lowest common denominator, but for the users you will actually have, and usability test participants should be recruited with that in mind.
There is some merit to what I assume is your underlying argument, but the way you phrase it isn't helpful.
There is some merit to what I assume is your underlying argument, but the way you phrase it isn't helpful.