Of course they are. That's why they distract so strongly from the central point.

Even if they distract more from the central point, theya re still real. They still have some potential relevance to the reader.

I think it would be a disservice to train someone up in the arts of rationality only to have most of their thoughts revolve around the facts of some fantasy universe.

Also, just because our universe _is_ more detailed than fictional ones, doesn't mean that all of that detail has to be available to the reader. We can offer simplified descriptions of situations.