Sumoudou is a search for Meaning. That's what gives it Value and differentiates it from Sports which have no Value.
What is Meaning?
Every human action has a Meaning, be it a Meaning of little significance or of great substance. Meaning is the Value the action has based on its goal and intent.
Sumou is not the Meaning of Life. However following Sumoudou gives you the power to forge your body in the fire of your will, overcome yourself, and obtain true Power to seek the Meaning of Life.
What is of little, insignificant Meaning is valueless. Only things of deep Meaning have Value. You should not bother yourself with anything else, unless necessary.
Once clearly seeing the purpose and intent of things it's easy to ascertain their Meaning.
Sumou's purpose and intent is Trial of Power - Sumou is Chikarakurabe. That's why Defensive Sumou is always Bad Sumou and anything else than Power Sumou has no Value.