Readers All Over The World
TL;DR
As an online writer, I can have a global impact by reaching readers all over the world, thanks to the asynchronous nature of the internet. My words can travel far and wide, reaching people in different locations and even in the future.
One of the greatest things about writing online is the async impact you can provide to readers all around the world, from now onwards. It's as if by publishing a photon is created that can shoot off and spread in any direction, landing on the eyeballs of a passerby thousands of miles away, or years into the future.