How do large companies keep growing despite communication breakdown?

I don't know where else to ask this question…no other subreddits seem to fit…so here we go… Iknow all about economies of scale and diseonomies of scale. So how is it that companies can grow, be profitable, and successful despite huge communication issues internally? I guess to be more specific, not just that departments don't talk to each other, but that departments have goals that directly compete with each other. Would love to hear from anyone who's worked at a C-suite or middle management level, but really anyone who might have an informed opinion on this topic.