alt Hacker NewsGerman culture is very functional, rigid, and dry, and it serves people with that kind of mindset very well. However, it clashes strongly with typical Southern cultures, so it is no surprise that the parent mentioned this. People who value the "softer" aspects of life are not going to feel at home.
There are certainly exceptions, and YMMV.
That's a pithy description of it all. If I hadn't met my (Greek) wife in 2015, I've probably would have left long ago.
And to come of think of it, I think there is another aspect that influences this: Germans are not having as many kids as the immigrants, so the overwhelming majority of the kids in the kitas and schools are from immigrant families or immigrant/native mixed parents. This means that (at this stage in life) any new friends you get to make are likely through your kids, and even there the pool is selected against Germans.