Comment by BasouKazuma

You got it right! Since each user is paying less per chapter read, you need more subscribers on the service to surpass the revenue that would have been received with a-la-carte only. And there is a huge opportunity to get more subscribers paying to read than there are people paying under the traditional a-la-carte structure due to the much lower barrier to entry. This is exactly how Crunchyroll pushed the anime industry forward where physical sales are mostly downstream from digital subscription services.