and to go a step further, it provides something to believe in (different from just a religion replacement) with simple morals and clear, elevated pro-/an-tagonists, something that's rare in the real world.

it's the modern version of aesop's fables--a way to share morals across a society through stories.

american westerns and chinese wuxia/xianxia are similar, simple morality tales wrapped up in different situations with heroes who rise out of the ordinary to do the extraordinary.

it's the simplest cultural glue.