What

Right now each instance (node, baker, accuser and DAL node) are not strictly related to others, while in practice they are.
Creating a group of instances ties themselves together with shared config values.
For example, if we create a group of instances (let’s call it “mainnet-setup”) and install a node and a baker instances, we force the baker to use the node port value.

Why

This simplifies a lot the initial setup and avoid human error.