I'm just a noob here, so my opinion may be miss-placed, however, from what I have seen so far, I would say that by holding SP, you attract more upvotes from people curating than if you had less SP. The noobs mostly seem to gravitate to the whales and dolphins in the hopes of catching some scraps, while other whales and dolphins don't want to waste their votes on minnows. So the more SP you have, the more you attract upvotes and the more you make. When you power down and lose your voting power, you become less desirable.
Like I said, this is just my observation and since I didn't do any in-depth study of it, I could be way off the mark.
Nods, yeah. I think that is what I thought was going to happen. :)