Slightly tangential, but I've been watching Duolingo go down this road for the past few years since one of Zynga's product people became their head of product. Duolingo was never the best way to learn a language, but it's increasingly become essentially useless as an educational tool as they push for more and more revenue from their "whales". Every aspect of the experience is shaped towards manipulating people into "engaging" for longer and keeping them coming back, ostensibly to make learning more effective but in practice at the expense of learning.

This blog post by their head of product is a great example of the problems in the industry—he talks gleefully about all the manipulative techniques he pulled in from Zynga, and doesn't seem to have any clue that he's sacrificed the mission in pursuit of relentless growth.

https://www.lennysnewsletter.com/p/how-duolingo-reignited-us...