Why should a service level agreement include bundles of metrics?

Individual metrics without a specified service context are unhelpful. They should relate to defined outcomes and not simply operational metrics. This can be achieved with balanced bundles of metrics, such as customer satisfaction and key business outcomes.

https://www.bmc.com/blogs/itil-service-level-management/#:~:text=Service%20Level%20Agreements%20(SLAs) &text=Individual%20metrics%20without%20a%20specified,satisfaction%20and%20key%20business%20outcomes.