I mean the main reason is that (at least then, but somewhat so today) the largest newspaper publishers in Germany and their biggest literature publishers were t

I mean the main reason is that (at least then, but somewhat so today) the largest newspaper publishers in Germany and their biggest literature publishers were the same people, honestly. But it meant that the press were very much on side. They probably also felt that their archives were more valuable pre-internet. Germany also just has a tradition of very strong authors rights.