Specifically, if you have a team that doesn't communicate effectively on a daily basis, then the standup gives you -- the manager -- a place where you can get and keep your developers on the same page.
When everybody already knows what's going on, then the standup loses a lot of its meaning, and should get cut down to "Anybody blocked, or need anything they don't have? Everybody good to go today? Okay, let's make this happen."
But at a lot of companies, it goes the other way, turning into a Kafkaesque version of Show and Tell.
Most people that end up in technical management don't get any serious coaching on leadership or management. This leads to a lot of management-by-bestseller, cargo-cult agile, and the sort of dystopian teams that grind the minds of otherwise talented developers into useless pulp.
It's not that these managers are incompetent or bad-intentioned, just that they never got any solid guidance on how to lead, manage, and grow a team.
What's truly insidious is that the problems don't really start becoming catastrophic for months or years, by which time it's very, very difficult to turn the ship around.
One of the more powerful tools for fighting this sort of problem is the retrospective -- a weekly block of time where the team goes over what works and what doesn't -- but, more often than not, the retro is the first thing that gets cut from the process because "nobody has time."