This is a very narrow take on what validation is and what it's used for. A better example would be managing resources, what operations you can perform, what res

This is a very narrow take on what validation is and what it's used for. A better example would be managing resources, what operations you can perform, what resources are assignable to what groups etc, are all validation and if you don't have that structure on the frontend your UI is as usable as picking a date by writing a cron expression. No one is saying you don't need this logic on the backend. What we are saying is you need it on the frontend too, otherwise you don't have a UI to begin with.