The frontend team case in point didn't actually have any managers. That's complicated because what you're buying there is a group of people with already-set practices and that works well together - if you're not careful, you'll end up with a "silo" that just doesn't communicate with the rest of the company.

That kind of thing happens when a big company acquires a small startup, for instance (and it's the main reason I always see acquisitions/acquihires failing spectacularly) - again, all anedoctal...