The issue with this framing is that understanding something isn't a binary; you don't need to be an expert in every feature of a programming language to be able to write useful programs in it. The comment above describing prototypical inheritance as esoteric was making the point that you conflated the modulus operator with it as if they're equally easy to understand. Your responses don't seem to indicate you agree with this.

It sounds like you expect everyone to understand 100% of a language before they ever write any code in it, and that strikes me as silly; not everyone learns the same way, and some people learn better through practice than by reading about thinks without practice. People sometimes have the perception that anyone who prefers a different way of learning than them is just lazy or stupid for not being able to learn in the way that they happen to prefer, and I think that's both reductive and harmful.