There may be a difference between boolean and gradient rewards. Consider that fitness apps track progress over time, and can raise/lower the bar to provide you the motivation you need to continue. It also provides a measure to show that you are improving.
It's also making an untenable thing, your health, into a concrete number. This can keep it real for some people. It's using a parallel domain to assist.
Compare to badges which don't show progress, nor are they individualized. I think these considerations lend a lot to the balance of pros/cons.
If we did wish to encourage regular writing, it mike make sense to show a meter of how many articles you've written in a week/month. Or to provide a goal to enable that sends reminders.
I think each game system needs to be well evaluated for the user's needs. I think the more natural it feels, the more helpful it will be -- though I might need to track down some studies to see if this is true.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.