Another ramification would be before a taanis. Often, someone will drink water before a taanis to give extra hydration. Unless they’re thirsty, they would not recite a brocha.
That is just not true. They are deriving benefit from this world so they are obliged to say a bracha.
Where does it say anything about flavorless food? The Mishnah and Gemara mention water.
It’s the exact same principle. Eating flavorless food is exactly the same as drinking water. If it’s for nutrition you say a bracha, otherwise you don’t.