Every time I visit I am genuinely impressed with how insanely wrong and inaccurate the answers all are. Even if it’s something straightforward with a single, verifiable, objectively correct answer that anyone can look up in a few seconds, people will somehow say something incorrect.
It has a strong effect on it. A lack of a common language makes it more likely for a culture to fragment, and a widespread common language causes it to grow closer together. I wouldn’t say it’s essential though.