To simplify this, let's make the proper distinctions between author and curation rewards. For purposes of this discussion, let's focus on the former first.
In the name itself, it is a reward for authorship whoever how we use it has evolved beyond that such was the case w projects such as Utopian, which adds additional utility to that functionality in rewarding off chain development while the DAO was but a glimmer in the whales' eyes.
But, you see, in either case, the reward is not for nothing but to reward some form of activity.