Depends on how you define power, and the article is defining it as influence. Do Jack Edwards reviews influence a substantial population of people to buy/read certain books? Seems like yes. If he's the world's most powerful, that depends on if others are _more_ influential. I personally don't know of any individual who has as big a following that influences reading. So the claim holds for me and doesn't seem hyperbolic.
Depends on how you define power, and the article is defining it as influence. Do Jack Edwards reviews influence a substantial population of people to buy/read certain books? Seems like yes. If he's the world's most powerful, that depends on if others are _more_ influential. I personally don't know of any individual who has as big a following that influences reading. So the claim holds for me and doesn't seem hyperbolic.