Power is a Lodestone
One of the hard things to convey in a gameworld is why the high level PC/NPCs are not out there “taking care of things”. For example, if 1st level PCs discover a plot that is way bigger than they are, why not just get Rags, Aria, and Garret off their lazy asses to take care of it. The stock answer is they have their own worries, adventures (and in the case of the aforementioned heros, orgies). Another (esp for NPCs) is politics and machinations. And lastly, why should anyone believe these little 1st PC peons anyway? I have always found these answers to be less than satisfactory.
One concept that is prominent in the Malazan books (see thread on books in the Lounge) is that power is a lodestone. If one high level dude sticks his nose in someones else’s business, then others will as well (some opposite, some just seeing if they can get an advantage). As an aside, the Malazan series does detail a number of these power convergences and they are Epic in nature. So if Rags goes on a rampage against some group, the battle will quickly escalate as old enemies and now powers converge to the scene. Thus, he will likely pick his spots to unleash his powers.
It has a nice appeal but I wasn’t sure if it was “realistic” even in the fantasy space. Then I noticed something in WOW—the exact same thing happens on the PVP servers. High level PCs hang out in high level zones “doing their own thing.” However, every now and then a high level PC decides to go pound on low level PCs (ie, go to an area where most of the adventures are lower level). Say a Level 70 horde rolls into town where most PCs are 20-30th level. Unless there are about 40 PCs, the L70 is just going to rampage around. There are NPC guards, usually a good 10 levels higher than the regular PCs (say 40th level). But they will not be much of an issue so long as the L70 is careful. But the interesting thing is that there is a reaction. In most cases, L70 PCs from the Alliance will show up and go after the rampaging horde (note: I presume this happens the other way as well, just my experience has been from the Alliance POV). How does this happen? Well, most players know someone at high level and can just IM them in the system if they are on. Of course, some may have their own high level PCs from prior play and just log out and back in with their old PC. Regardless, there is communication the travels rapidly (each zone has their own defense chat channel as well and “X area is under attack” pops up when a bad guy kills one of the good guys).
Thus, I think if we add Power is a Lodestone to the typical reasons, this does help with the question “who doesn’t X help”, be it a god or epic level PC.