To OPie: At first, influence is strictly local. As world views are strictly local in a world with low to no long distance communication, one's actions are major events in the lives of the people around them. Your PC is personally known by folks who aren't afraid to come up to you and give you free things. They know you and you, by your actions, have come to know them.
As you move up, like those who climb the authority ladder, you move away from local events, but have greater perspective upon what is going on. You learn the causes of the orc attacks and the trade wars to the South. You know things about your world others do not because you have taken up the opportunity to explore it. It's you who puts 2+2 together and now can take action to stop root causes.
By the time you've discovered, shared, beaten, joined powerful people and organizations, you've basically moved beyond your home, family, and friends. You have reached a level of power rarely seen by anyone you've heard of. Like a high level leader in our own world, the little people are harder to connect with. You don't know all the small customs of all the places you go, but you may have greater influence over their futures than they do.
As D&D is more medieval, things tend not to get more than continental. "Conquering the world" means a Roman Empire or Chinese Dynasty. There's more world out there, but it's never had any influence for centuries, perhaps eons. An epic level travel exploration might have one empire conquer another. It might mean traversing the globe. It's going to places where none have returned. This could mean falling off the edge of the earth or traveling to breaching between two dimensions, or starting all over again as explorers in impossible lands like Faerie or Shadow.
IMO, dealing more with religious places like the heavens, hells, and Outer Planes (Valhalla for example) is not Epic, but outside of life. Sure a visit might be possible, but doing something adventuresome there is hard. I've read Sepulchrave's storyhour and I think that gets about as good as it gets. Maybe someone becomes a god, but I don't that level of sophistication could be had on a broad scale. IMO, the game is easier to understand at the you and me level. I'm no PhD in religion.
Does this mean mean PoL breaks down? Yes, but only if you take it to levels it was never meant to go. Things like vast metropolises or modern society as the default setting. Open and instant communication everywhere means no exploration is needed. Enormous libraries accessible to everyone holding all the knowledge you'll ever need to know = ditto. Widespread education teaching people about places and things beyond = again.
Medievalism and learning the game as you go gameplay only hold up in certain cases. I think it's why Alpha Omega and Boothill hold up, but others require a different kind of RPG.