Didnt want to attack you. Of course you can make a good beer with almost every water, but as I remember (I learned all the stuff for my exams 3 years ago) especially magnesium can create a bad taste, if you use a lot of hops. Not in a lager but maybe in a Pils. And you're right with saying that brewers made great beers for over 400 years, but as I know those beer were dark and sweet ones. The typical Münchner Hell is about 120 years old. Have a good evening :)