I don't think that is what the parent said, but I'm afraid my comment was too snarky (apologies), and the audience in this thread is not eager to be changed in their beliefs. Thanks for taking the time to reply though.

LLMs are fed a lot of data, and there are many patterns in there, including reasoning and some logic. Adding a little domain specific data will not immediately learn that domain, but it will also not be limited to only that data in its reasoning.