The humor is playing on an inclination to laugh at things we don't understand, which seems counter to the hacker ethos. Software is hard, and there may be deep reasons in the dynamic type systems that cause these languages to work like this, or there may not be, but either way this type of thing is interesting and seems to demand some further explanation and/or justification. I find it interesting but don't get the humor. Perhaps, as you implied, I'm just too old.