Sure, the count is tracked by the company Duolingo, but that's irrelevant. The count is also tracked by the user, and that's what's important. Even more importantly, the commitment to keep to the count is made by the user. It's their commitment, not Duolingo's. Therefore, it's not relevant that Duolingo encouraged that commitment and benefits from it. The user is still going to be subject to the guilt and shame that comes when humans break our own commitments, and that's what makes quitting easier said than done.

It's kind of like telling a smoker to just quit because it's the smoking company who benefits. Yeah, sure, but the addiction is internal. They're not just selflessly smoking to help Philip Morris.