Because complicated things become so obvious and natural that it's hard to even remember that some things are not inherently known by any of your peers. It can

Because complicated things become so obvious and natural that it's hard to even remember that some things are not inherently known by any of your peers. It can be hard to accurately gauge your interlocutor previous knowledge, so you don't make them feel dumb by explaining too simple things, or by starting with too complex stuff. >or point to obscure or very high-difficulty resources. Although here I think that's on the learner to make an effort. If you want to learn X but you need Y to understand it, your next question should be how can I learn Y, and if you need Z to learn it, you should ask how to learn Z, and most of these questions can be answered by search engines, you don't usually need an expert for that. "E.g: You ask an expert programmer for advice on how to learn to become a good programmer, they will almost always suggest mid tier resources." Well once you went through something like CS50, you should be able to grasp mid tier resources, or at least be able to find out what you need to learn to go through them.