The best movies aren't

Huh?!

That's the usual response to deep thoughts.

I began thinking about the best TV and movies I've liked, and most of the reason that they were above-average is that they weren't about the genre; they were only set in the genre.

Mister Roberts is a WWII film taking place on a naval vessel, but is NOT about war.
The Shootist is a western, but not about shoot-outs.

I'm sure you can add to the list, it's a long list.