It writes that way because almost everyone writes that way these days. It's annoying if you learned English grammar from textbooks and other materials written o

It writes that way because almost everyone writes that way these days. It's annoying if you learned English grammar from textbooks and other materials written over 50 years ago, but it's extremely common now anyway. So a large chunk of its training data will be that way. It's interesting, because all the older works in its training data will default to the masculine singular, and that has to be a massive number of books too. But maybe the modern writing, including lots of online sources, simply overwhelms that. Or it's one of the guardrails written into the AIs to avoid offending people.