No and I’d say diversity is worth over a homogenized society even if it comes at an increased chance of conflict. And it’s not like people who live in the same country and speak the same language don’t fight each other. People argue over mundane stuff like tv shows after all, and get into online wars and exoduses over social media platforms.

The peace you seek is probably only possible through massive brainwashing or an absolute privacy infringing totalitarian state that monitors everyone and is rapid in exterminating dissidents that are flagged for abnormal behavior.