For a lot of folks eliminating aspartame fits the spirit of n=1. We have enough grief trying to make sense of steak and potato data, additives are just an unwelcome variable.
But I agree that--considering the consumption rate--I would expect the evidence of harm to be more clear-cut.
Lots of: urban hiking, cycling, sprinting
Lots of: fresh meat, seafood, eggs, organs, tubers, starch fruits, vegetables, meat fat, dairy fat, oil fruits
Some: cured meat, dairy protein, sweet fruits, rice, pulses, tree nuts, oil seeds
Minimal: soy, refined proteins, sugar, liquid carbohydrate, grains, refined oils, peanuts