I look at it from this perspective...from the beginning people did not drink from the rainwater directly falling from the sky, it was collected from the earth where it picked up the inorganic minerals that were available, although there is record that some collected rain in clay containers, which, by the way, conditioned the water with mineral elements. In general our ancestors obtained water from streams and wells. These were hard waters with inorganic minerals in them, and in much higher concentrations than today!
I would also like to point out to you that rainwater is really not like distilled water at all! It appears that raindrops do carry a trace amount of minerals (see study below); also I suspect that the fall from the clouds through the air has an effect on the rainwater’s molecular structure and as it passes through the oxygenated atmosphere it is transformed in a way that distilled water cannot compare to!
Studies of the chemical composition of rainfall have been carried on for many years starting in late 1880s in the United States and in Europe. Rainwater collected in various parts of the USA contains (in milligrams per liter): Fe (0.015) , Ca (0.075-1.41), Mg (0.027-1.2), Na (0.22-9.4), Ca (0.075-1.41), K (0.072-0.11), HCO3 (4-7), SO4 0.7-7.6), Cl (0.22-17), NO2 (0.02), NO3 (0.02-0.62), and Total Dissolved Solids 8.2-38), and pH of 4.9 to 6.4.
The rain falls to the earth onto rocks and soil and because it is an empty structure it picks up inorganic minerals, which now gives it a life force-energy. This “electrified” water then energizes the plants and all other life on earth.
Minerals electrify water, they give it a life force, something we all require. Water that is DEAD without a life force cannot be good for us and that is how I see it.
If you look at the molecular structure of distilled water compared to mineralized water the picture says it all...distilled water simply doesn't look as good!