Anthropic Skills is powerful for the same reason my old Code Sprouts project felt unreasonably powerful to me a few years ago.

Giving just a teensy bit of structure to the LLM (in that case, a Typescript schema for state), and allowing a hierarchy of english language instructions that the LLM could peek inside if it wanted but not be bothered with by default.

An example of efficiently unlocking the LLM's ability to create software.