In some areas, you need to control precisely what goes where, and when. You need to achieve high throughput and/or low latency. You can't just install N x M con

In some areas, you need to control precisely what goes where, and when. You need to achieve high throughput and/or low latency. You can't just install N x M connections but need a suitable architecture to minimize the amount of pipes as well as keep a flexible connectivity. A lot of thought goes into the architecture at a global scale, it isn't just the local "here's two ends, let's glue them together". In fact if there's a lot of that something is wrong.