Necessary and unnecessary ...

Needless because frankly the book is nothing but a fun Quidditch history, followed by a listing of virtual teams in a virtual championship ... Not really interesting. Of course (and it's not a mystery) the book makes no mention of Harry. But necessary because after all this book gives consistency to the novels of the universes of Harry cycle and especially because the profits are donated to a charity. If we add that the price is low, why do without a good deed while having fun?