Language is an absolutely critical part of community, identity, socialization, and connection. Even just not sharing the same first language as another person begins to chip away at these metrics. Much moreso if you share no language in which you are both thoroughly fluent. It's not either person's fault, and it's true even if both parties have absolutely no racism or xenophobia or whatever in their hearts (though isms multiply the effect - even the unconscious isms that most people supposedly harbor).

That is a point that could be made in the essay! I don't think it's a given, but it's treated as one. My experience is that children who are ESL assimilate pretty heavily.