what is my "health" and how does it affect me?
If after reading this you decide you don't want to deal with health (and I stand by the community when I say: nobody here likes health), start using the Duolingo website. No health, as well as grammar notes can be found on the website.
Regardless of public acceptance this is what I don't get... they release what they consider to be a useful feature but right from the start they say they won't bring it to the PC... So, it's bad to binge-learning on a mobile but it's ok on a PC? So much for logic...
I suspect that the true reason they want to cut down on people binging on mobile devices is the possibility of eye damage through peering at tiny screens for long periods of time. Obviously that are not going to admit that, though. People using the web are probably using a desktop or laptop so there is not problem, there.
I though about that and it would sound reasonable, but then again by their own admission:
*Why do we have Health?
Because it’s better for learning. Our research shows that if people advance too quickly on Duolingo in one day, it can actually negatively impact their learning because they are less likely to remember what they’ve learned. We know that users learn best when they study every day and take the time to practice and review what they’ve learned. The Health feature encourages users who are making mistakes to take a breather and review previous lessons before moving forward.*
If theirs is a reason regarding too much smartphone usage then it's an unusual altruistic concern for a company of its kind.