Splitting up SP among different accounts provides no platform advantage.
100K upvoting a post or 3 accounts with 33K upvoting a post is the same.
The white paper even spells this out....there is nothing gained by splitting things up other than hiding one's identity.
I think I am saying the same thing with the added point that when whale accounts are split up it gives an appearance of decline of number of whales.
The anonymity is going to make it close to impossible to determine the extent of the dilution of power on the platform. The rewards pool which is approximately 50,000 Steem daily helps in spreading the wealth. The bid-bots and curation claim some of that back to the whales, I would guess maybe around 10K to 20k Steem.