Wow - people do that? Jesus christ.
When translating, I purposefully always change third persons to they...
At least when I was in school, it was always one of those things like "never use singular 'they', always use 'he or she'; don't split infinitives; don't end sentences in a preposition" kind of grammar prescriptivism that always seemed like it was being taught "because that's what The Book says is 'correct' and that's what I learned when I was in school" etc.
At least at the time, it never came across like some anti-non-binary thing, just another one of those hold-over rules from like the 1800s that was arbitrarily made (usually based on rules from another language, like Latin or French) to distinguish high-class, educated people from lower-class people, or whatever.
As it turns out, singular they, split infinitives, and ending sentences in a preposition are all pretty natural in English and have been around for centuries. ¯\_(ツ)_/¯