The Earth civilization and the Terra pre-epoch civilization are both civilizations built upon 'everyone'... every person contributes to the civilization, every person is a part of the civilization, they are all the strength of the civilization.
Such a civilization is relatively equal and more adept at cooperating to overcome challenges. However, a civilization cannot be perfect. This collective civilization, facing the relentless extraterrestrial fireseed creature invasions that cause massive destruction and casualties each time, even if victorious, severely damages its own potential.
The death of a person is very important to such a civilization.
Therefore, for survival and continuity... when confronted with the endless interstellar invasion war during the Lost Epoch, Terra civilization could only choose to step onto another uncertain path that ensured survival.
The path of a Sublimated Civilization.
