Also in regards to accuracy, weight never changes.
Volume fluctuates depending on temperature.
Weight does change around the world, mostly because at the equator you are farther away from the centre of mass of the earth than you are at the poles, but also because of local gravity anomalies.
It's mass that never changes, so maybe we should all get an inertial balance for our kitchen!
Unless you are measuring ethanol, which is more like 0.78g per mL.
So his method comes with additional health benefits for free.