That might be a bad example ... replace english with nearly anything not related to prompting/coding. For example, I bet the models have "knowledge" of biology, chemistry, etc. not exactly useful for programming a SaaS web app that say does project mgmt. I think there's opportunity for very specific tooling rather than "general" knowledge.
I don't train LLMs myself, but my impression is that general knowledge has lead to more intelligent behavior on specific tasks. The voluminous training set is imporant.
But even besides that... Yesterday I prompted a feature by referencing a specific Monty Python skit. Does the coding tool need to know Monty Python? Maybe I could describe the feature in other terms, but it sure was convenient to have this shared knowledge. I don't see why Shakespeare would be any different.
What language do you plan on prompting it in?