Great to see this discussion. My son displayed a science project on negative differential resistance 21 years ago. Had quite a few electrical engineers passing by with "the low brow" look. His device involved carbon fibers arranged in a cross shape placed inside of a cement mixture and compressed to ~8,000 psi during the cure stage (following the example of some published research).

I'm guessing by the opening that the author is a fan of the ExpeditionaryForce series which features an AI named Skippy.

I think it is very funny that the author has decided to start with a layman’s introduction to the concept of resistance after saying that you need familiarity with the behavior of operational amplifiers. Who is in that category of familiarity while still not having an intuition for resistance? Perhaps someone but how.