There are pros and cons, and it can be used for good or bad, just like any other form of marketing. I think it‘s good as support sometimes, like MyFitnessPal has this day-streak. I‘m not using it for the points, but on harder days it‘s helping to log in and track those calories.
One detail I like about certain forums and also Hackernews is the abundance of profile-images and the names are printed subtly. I almost never care or see who wrote a comment, which isn‘t the case in most comment-sections or communities.
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.
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