It strikes me as an Oder of operations problem.

If the system prompt is “flesh out template y with thought x” the form drives the generation, it feels compelled to use the whole template.

Of the system prompt is “refine thought x and then format it with the appropriate parts of template y” it becomes a simple transformation and formatting.

A lot of current gen llm pain appears to be being in the early days of understanding the nuance of system prompts.