Germans were more vassalized post-WW2 and have therefore a higher adoption of english than e.g, the french. Another consequence of the marshal plan is that yankee's wanted Germany as a consumer market and hence german culture is more closely tied to yankee culture than other countries, a lot of our shows, books, movies, music etc. are translations from english or not even translated in some cases. So there is more in common to talk about. Add to that there are a lot more germans than finns or dutch and I think it makes sense that german is the most endemic non-english language on lemmy.