By only blocking these 18 books, nobody would have taken much notice of this. By blocking all German users from the site, they will get a lot of media attention, and S. Fischer Verlag will get a lot of bad press. Whether or not they will move from their position is questionable, but it will hurt them.
Just sent a small donation to PG.
Making an effort not to buy books from that publishing house ever again, and telling all my friends about it.