To be fair, Eyeo/ABP deserved everything they had coming at them. They not only blocked ads, but there was code found to replace Amazon affiliate links with an affiliate id from them. (German report here - look for the part about typoRules.js.)

Even then, are shops selling kitchen knives (mind you, despite the name, youtube-dl can be used to download videos from various sources) held liable for people doing murders with them?

EDIT: On a sidenote, the Hamburg courts are renowned to know jack shit about technology and often produce rulings against any common sense.