To get a bit more into detail on this issue: In German, nouns referring to occupations generally are all gendered, where the base word is male, and the suffix "in" changes that to female. In cases of mixed groups, or where the gender doesn't matter, the suffix is not used:

Singular: Studentin = student (female) Student = student (male, or unspecified) Plural: Studentinnen = students (all female*) Studenten = students (at least one male, or unspecified)

Feminists (correctly) identified this imbalance as an issue of sexist language. The problem is, there isn't an easy fix. The common solutions nowadays are to use phrases like "Studenten and Studentinnen" (creating the new issue of which gender to name first) or in written form "StudentInnen". That's kind of clunky, creating a desire to use ungendered words where possible. So then people come up with constructs like this because they happen to be ungendered (but horrible in other ways).

I think in Austria, using the female form even for mixed/unknown groups is relatively common nowadays. But I'm just a very occasional visitor there and I'm not certain about the details. (Do they throw dice to determine which to use? Or did they just switch to the female, which then could be interpreted to be sexist against men.)