Treating performance and reliability (which is inescapably impacted upon by performance characteristics) as externalities is a great way to create perverse incentives for your engineering team.
Also this reads like a cry for help:
> Therefore, to keep our Kubernetes clusters optimized, it would necessitate mandating all teams to perpetually engage in complex manual optimization processes indefinitely, or until Mercari goes out of business.
Also this reads like a cry for help:
> Therefore, to keep our Kubernetes clusters optimized, it would necessitate mandating all teams to perpetually engage in complex manual optimization processes indefinitely, or until Mercari goes out of business.