Pretty sure it has something to do with "recurrent revenue". Having 100 subscriptions means you have a guaranteed that the in the next month you will get 100 * cost in. On the other hand being a pay perview model leaves you to the risk of having high fluctuation of costs. Payperview I see it favored for content providers who provide high cost content once in a while. On the other hand, making a subscription based model works better for content that you put out fast and at a relativelly low cost IMO