The systems we can build today with a small team are much more complicated than what we could do ten years ago. It's just that we also somehow managed to solve essentially the same problems we solved ten years ago with much more complex software.
Larger teams also ship faster, there's a lot of complexity to enable that collaboration.
Like what? Earlier systems worked if your computer worked. Adding a server is a DRM move and doesn't help the user with reliability - usually the opposite.
My experience is that in most situations larger teams ship slower, precisely because of the collaboration costs you mention. There are ways to reduce the dependencies, but most organizations can't get there.