The author says "reluctantly, but unavoidably america a world power" does he mean by this, why was america reluctant to become a world power?

The US wanted to isolate itself from the world. Now, since it was a world power, it won't be able to isolate itself since it is now intermingled with the rest of the world.

Communicating with the dead was common, it wasn’t seen as bizarre or weird,” explains murch. “it’s hard to imagine that now, we look at that and think, ‘why are you opening the gates of hell? ’