Yeah, it’s not very common that someone gets sued for insulting someone else. Still, about 235.000 in the last year, cases is still a higher number than one would expect. (Source: de.statista.com/…/polizeilich-erfasste-faelle-von… ) As insults are an “Antragsdelikt” they are only prosecuted if someone files a police report and sues.
I tend to disagree with the notion of “being super petty” for suing someone over insults. Sure, there are quite a lot of them, I agree with you so far. But I think about a lot of worse cases, where people can even suffer from psychological damages, e.g., if they are being bullied that way. Or if such insults are coming in regularily and/or are very intense in their expression.