Having expectations that any person should be able to teach what they can do to the rest of the team in a timely manner is unreasonable.

Problems like "Make X take less than Y time to run" or "Reduce binary size to Z" or "Design a fault tolerant system accomplishing Q" etc are often impossible for most to solve since they simple don't have enough foundations and intuition to solve them. You'd have to spend years drilling fundamentals to get people to that level if they are even capable of gaining the same intuition, most developers never gain those skills no matter how many years of experience they get.