what do theorists do?

Suppose we don't take the answer that theorists are smarter than other people.
Theorists develop frameworks. They develop languages that link multiple fields together.
The non-theorist is the specialist in a certain sense. They learn a certain language that directly relates to concrete facts.
This language is typically not big enough to easilly cover relationships to other subjects.
Let's say a politician knows a whole bunch of people and how to get certain things done in the context of the existing relationships amongst those people. The political theorist doesn't necessarily know those people. The theorist takes the words that the politican uses to describe what they do and works out the relationships amongst those words. Then they throw in something else, say economics. Then they put together a framework that combines all these terms and concepts together and says to the politicians that they can get things done better or do the right things if they take this economics piece of the language into account as well.

Maybe I'd better leave this as an open question.