First off, you wouldn't need to do that specifically. You'd only need to know that most of the people you talk to are above an 80 IQ on any given topic, in fact

First off, you wouldn't need to do that specifically. You'd only need to know that most of the people you talk to are above an 80 IQ on any given topic, in fact most people are about a 100 IQ on any given topic. So you already have a reasonable baseline for comparison. Secondly, I'd say you're likely the one missing OPs point by trying to take a mostly colloquial statement about how ChatGPT is about as informed as the bottomish X% of the population on any given topic and trying to be pedantic about it. Furthermore the real purpose of OPs point is that the X% is now a lower bound, even if X isn't 16% but 5%, it's only going to go up from here. Yes there's evidence of diminishing returns with the current architectures but there's also a lot of room for growth with newer architectures or multimodal modals. I think most people understand OPs point without having the need to go around asking everyone what their IQ is. There are numerous indicators, both formal and informal, that indicate that ChatGPT is as informed on most any given topic as the bottom 16% of the population. In fact, it's likely much much higher than that.