It could also be seen as adapting the business model to fit the process. Essentialy, the goal was to sell a product that guided users to learn in the most effe

It could also be seen as adapting the business model to fit the process. Essentialy, the goal was to sell a product that guided users to learn in the most effective way possible. The learning model is spaced repetition, which requires users to use the product over a long period - therefore the best way to sell it is as a long term subscription. If the best way to learn was to cram as much as possible in as short a time as possible, then maybe the product would be sold as a bunch of individually priced courses paid in full up front. As long as the product is fairly priced and provides a valuable service, there's nothing wrong with making money as effectively as possible with it.