Why network segmentation a good idea when managing a large network?

These are the following advantages of network segmentations:

1. Improve Security.

2. Easy manageabilty by making one segment for each group or department.

3. Lessens network congestions and slowness, by preventing unnecessary broadcast storms on the network. 

Advantages :

1. Better Managed Network,

2. Less Network Traffic which in turn improves Network Performance,

3. Enhance Security.