So, first, we have to look at the composition of the "mystic" water. As you can probably tell, this ain't normal water. There have been many myths about "magical" water. For example, the fountain of youth. A spanish explorer was looking for this fountain stay younger, his name was Juan Ponce de Leon. He literally found florida on his search, which shows the absolute dedication of this megachad. Anyways, from this historical example, we can see that water has always been some sort of "fabled" substance that is mysterious. This inherently makes this "rare" water already kinda mystical. Second, you helped me massively with one of your points. It is a mystery. No one really knows what this thing can do. Because of human curiosity, anything that we do not understand is immediately researched because people want to find it. It is inbuilt into the human psyche. Finally, my last point. I apologize for this, but GaMe FrEaK lOgIc. At the end of the day, the games and the anime are WILDLY different. There are many discrepancies, and also just general wackiness that the games don't have. For example, the prices in pokemarts probably don't carry over to the game. And finally, some fancy things just don't sell in markets.
Sorry for the long answer >:)
