This was actually the whole original point of Duolingo. The founder previously created Recaptcha to crowd source machine vision of scanned books.
His whole thing is crowd sourcing difficult tasks that machines struggle with by providing some sort of reason to do it (prevent spam at first and learn a language now)
From what I understand Duolingo just got too popular and the subscription service they offer made them enough money to be happy with.
linearchaos@lemmy.world 6 months ago
Duolingo has been systematically enshittifying the free/ad supported service. Now every time you fart, you get a big unskippable ad trying to get you to subscribe to their service for free for 14 days without telling you the price. They took all that crowdsourced data that weren’t going to profit off of and are making the app a miserable experience without it.