> The game theoretic optimal solution for a service provider is to always validate

Which can be a mistake when the person you are dealing with has or may have an ulterior motive for your interaction (i.e. said "toddlers").

This is why in actual customer service, validating someone's feelings ("I understand you did not like the cook on the steak") is good, while validating their concerns ("I understand that the steak was undercooked") is bad.

You don't want to "find common ground" or "shared viewpoints" just to fulfill the validation matrix plot, because it may very well be based on a false premise, or even a blatant fabrication. In real world terms, validating concerns can often be an admission of liability or fault, or a soundbite that will be weaponized against you.