I'd be very interested to know exactly what metrics allow them to ignore the fact that their most-recent app redesign has been, from what I can tell, unanimously disliked and shown to frustrate their userbase.
This is exactly the example I was thinking of. There is a Reddit AMA where a user asks why they keep it even though it's universally disliked and the CEO essentially says "I hear you but DAU is higher on the redesign".
I think it's an example where metrics are taken too far. Yes, better DAU is good, but if you are alienating 100% of your power users and getting more engagement from your short-term, new signup users that's going to look great for a few quarters but kill your app over the long term as the community experts start telling everyone they used to recommend Duolingo to to go use something else.
