Not all disputes need to be adjudicated. It's undoubtedly a fact that the German concept of "defamation" primarily relates to situations that should never be adjudicated by any third party.
Genuinely, by far the most common situation where claims of defamation arise in Germany is any less than 5 star review left to a business on google maps.
The good thing is that google in Germany now shows how many reviews were removed due to deflamation. That should be enough for people to make their judgement when checking how many stars a place has