Why Are Researchers Just Looking to Treat Neurological Diseases Instead of Thinking of Prevention?

Alzheimer’s and ALS are just two of the neurological diseases with studies being done on the protective effects of lowering levels of free glutamate, see this, and this:

https://alsnewstoday.com/news/als-associated-cellular-toxicity-lowered-with-investigational-molecule-fp802/)

while the elimination of free glutamate, which is added to processed foods (in huge amounts), supplements, and drugs, is not considered.