Maybe top-down is not exactly the right way to describe it, but the point is that it is institutionalized and such institutions must have a degree of inertia to sanely function as an organization. Curie has a mission statement (an informal one at least). That's not to say it can't evolve, but people join knowing that mission (and likely supporting it or they wouldn't join), so it becomes self-reinforcing.

Individual voters who haven't institutionalized their decision making can and do more easily shift direction on a whim, as quickly as today's hottest pop star can be tomorrow's has-been. Steemsports is a great example of something that likely wouldn't have been popular or fit the mold of what voters were looking for a few month ago, but it successful now.

I started a curation guild to discover unrecognized posts and authors (and still have an individual dedicated curator doing that for me) but now I'm recognizing more value in people having at least the possibility of a critical mass of success and earnings in some (not all) cases that call for more focused voting. In some ways the smaller reward pool makes this even stronger as the amounts of very-widely-distributed rewards become increasingly meaningless (better to give at least meaningful rewards to a few, I think). So the pendulum swings on these things.