Dungeons are attracted to cities. On average, a city with four hundred thousand people will have a dungeon appear in it every day.
Only about one in fifty thousand people are espers. In a city of the same size, one can expect to find eight espers. The powers and power levels of espers vary, but one can expect that half of these espers will be no more helpful in dungeoneering than an unpowered person, whether in combat or support. Of the other half, three quarters of them will be of limited or situational usefulness. He knows that they use a letter grading system in the East: most espers are rank D or C respectively.
In a city where one dungeon can be expected to appear daily, one can only expect about two or three espers useful for sealing them.
What, then, are people to do?