The German brewers just *love* to witter on about their Purity Law. Apparently no-one else in the world brews good beer because no-one else has a Purity Law. Now, when was the last time I heard an argument like that? Oh yes, some religious nutter telling me I can't possibly live a good life if I don't have a Holy Book to tell me what is and isn't good.
Never mind that it was forced on the rest of the country by the Bavarians as a condition of unification and didn't cover the whole of Germany until 1906, never mind that it doesn't stop you using GM barley or hops sprayed with pesticide, never mind that it wiped out entire swathes of North German brewing tradition at a stroke, never mind that pretty much all British ales do indeed meet the Reinheitsgebot...
The Reinheitsgebot is a prop, a sop. It's what mass-market German brewers use to convince themselves that they are the best in the world and so is their beer, when they aren't and it isn't. Sure, there are some very VERY fine beers produced in Germany, but there's also a lot of meh and a fair bit of dross.
PS. I live in Germany.
PPS. Be pure! Be vigilant! Behave!