My understanding is the most benefit is to children whose teeth are still growing, then secondarily to adults who have substandard dental hygiene. An otherwise healthy adult with good dental care routines is the least impactful case.
Distilled water lacks even electrolytes like potassium and other minerals your body needs. So you may miss out on a bit of these micronutrients if you drink only the distilled stuff. Some studies have found a link between drinking water low in calcium and magnesium and tiredness, muscle cramps, weakness, and heart disease
My understanding is the most benefit is to children whose teeth are still growing, then secondarily to adults who have substandard dental hygiene. An otherwise healthy adult with good dental care routines is the least impactful case.
Going off on the tangent of distilled water: distilled water can reduce overall minerals in the diet. From WebMD https://www.webmd.com/diet/distilled-water-overview