Aspartame also rapidly
"breaks down into residual components, including aspartic acid, phenylalanine, methanol, and further breakdown products including formaldehyde and formic acid" on ingestion. [1]
Even with no smoking gun for cancer, why would anyone tempt fate after reading that?
You forgot the second half of the paragraph from your source:
> Human studies show that formic acid is excreted faster than it is formed after ingestion of aspartame. In some fruit juices, higher concentrations of methanol can be found than the amount produced from aspartame in beverages.
Also:
> Aspartame consists of two amino acids—aspartic acid and phenylalanine. When ingested, aspartame is broken down into these amino acids for use in protein synthesis and metabolism. In addition to aspartic acid and phenylalanine, aspartame digestion also yields a small amount of methanol, a compound that is naturally found in foods like fruits and vegetables and their juices. The amount of methanol resulting from consuming an aspartame-sweetened beverage is about five to six times less than that resulting from the same volume of tomato juice.[1]
Since who drinks tomato juice, really, another way to put it is that you'd need about 20 large Diet Cokes (32 oz each, no ice) per day to get the same amount of methanol as from a diet rich in ripe fruits (1000 mg/day).
Methanol basically comes from fermentation or digestion of pectin, so it’s in pretty much all fruits and fruit byproducts in small quantities. It’s really not a problem in small doses, in fact your breath will have a small but measurable amount of it at pretty much all times. You really have to try to get enough methanol to poison yourself.
First the dose makes the poison and second, all of those compounds are naturally occurring in humans as part of our metabolism. The pathways responsible for metabolizing proteins and keeping us alive produce them.
Just love how you selectively quote that paragraph. The following sentence is: In some fruit juices, higher concentrations of methanol can be found than the amount produced from aspartame in beverages.
In other words, all of those compounds are fairly simple small molecules and will be found abundantly in nature. There is no indication that aspartame leads to the breakdown of larger quantities then many "natural" foods.
Even with no smoking gun for cancer, why would anyone tempt fate after reading that?
[1] https://en.wikipedia.org/wiki/Aspartame#Metabolites