Great post! One thing to note for people new to Hive and or Splinterlands you should not be concerned very much with the KE ratio. Ratio of 3 and above means that you have received a bunch of rewards in the past and took it out of Hive and that is when you need to think about changing rewards to 100% power up and/or buying Hive.
If you are a new Hive user coming in as a Splinterlands player you can simply leave the default value of 50% HP 50% HBD and don't worry about it, because if you are starting from zero under these settings your KE ratio will equal 2 which is under the maximum recommended KE ratio of 3. 100% Power up means you are trying to grow your Hive Power as much as you can and staking all the HIVE you receive as author rewards. I am doing that and that would result in KE ratio of 1, but that is not talked about as required here.
It is exactly as you said. As a basic principle, if you don't change anything in your HP, your KE will be 2, which is a very acceptable value. You can use HBD to invest in Splinterlands, other Hive games, or even withdraw it.
The main idea is that, eventually, people will start considering the idea of bringing this resource back and increasing their HP. In more severe cases where KE exceeds 10+, the idea will be to stop providing support until these accounts align with the long-term investment culture.