I think the issue here is that I fundamentally disagree with the direction of this particular ribbing. I think we should be sensitive to this kind of naive questioning, which comes from a good place (wanting to make teaching easier and more effective) and can lead down productive paths where our priors are deconstructed such that we change what we think of as possible. We work in an industry where rabbits have been pulled out of hats and geese have laid golden eggs, by which I mean people have put their minds to hard problems and have come up with solutions that before seemed impossible and would have faced the ridicule that you're defending. To the extent that ridicule causes people to be less curious, we should be very careful about deploying it.