You can cut costs through optimization, but not always. Sometimes the benefits can be quantified in other ways. It may even mean spending more in one area to reduce costs in another (e.g. moving from on premises solutions to the cloud to reduce hardware and datacenter costs).
Cost optimization is often more a due diligence exercise proving you are getting the best deal possible, addressing any risks of over-spend and that you have proactively worked with a partner and/or vendor to reach the best deal for your organization.