Not sure the source but there is a rule in fiction that everything has a purpose, as opposed to reality. If the camera stops in an axe, you can be sure someone is going to wield it later.

There is no purpose in those alternate realities, other than being a sadistic fantasy, as another comment points to. Tarantino's universe is very familiar to me. It's based on the series B (or worse) films that we watched as teens.

There is an interesting exploration in Reservoir Dogs, Pulp Fiction and Kill Bill of the obsessive thoughts that old movies raised presenting extreme situations.

I do enjoy goofy details like Uma Thurman in the plane with a katana in the hand luggage. But this is part of the assumed over-the-top tone. Like you said, it's clearly delineated and presented as fiction. The others not so much. A counterfactual historic movie? Now it seems I'm supposed to learn about the plot before watching the movie, or just avoid Tarantino, because I've had enough of that bs.