What Makes a steem Whale or Dolphin?

There seems to be some concern about how certain steem holders can sway discourse, and potentially steer discussions, and even possibly game the rewards system of steem. To that end, some have speculated on what makes one a steem Whale, or Dolphin - Hive account@nanzo-scoop suggests at this early phase of steem, that

20k - 100k = "Dolphin"
100k + = "Whale"
Maybe it should be judged in USD worth?

Were that the case - that it was judged in USD worth - by Hive account@nanzo-scoop's figures, a Whale would be someone who holds ~$300,000USD of steem, and a Dolphin would be one who has over ~$60,000USD of steem.

• how much steem do you need to be a whale / dolphin / minnow
• Steemit: Whales, Dolphins, and Minnows- The Importance of Steem Power on Steemit
• Are you a whale? Or dolphin? Or only a tuna?!

Most of these threads seem to mostly agree: Dolphins are those with thousands of steem, Whales those with tens or hundreds of thousands of steem.

Are these accurate ballpark estimates? It will be interesting to see how these values may change over time.