Any good backend framework (Laravel, Django, Livewire, Rails) does server side validation out of the box without me as a developer needing to manually pass around JSON objects and continually checking their shape. The boundary between user input and backend code is well defined and border checks are easy.

> manually pass around JSON objects and continually checking their shape

Well Zod is a library that's typically used on the boundary.

I don't know why you're assuming stuff about a library that you've never used. No one would continually check their shape once it's validated at the api boundary.