Is that true and if yes, why?
"premium verum" is just a marketing-joke. Warsteiner is a real "Pilsener". And they brew according to the german purity law.
Martin (I studied Brewing Science in Weihenstephan and know Warsteiner very well)
As far as I read, Warsteiner is not a Pilsener because they don't use enough hops. It's like a Pilsener but less bitter.