[justarobert]

In that case, your objection seems to be to light weight or minimal frameworks rather than SPAs on this point. There are plenty of minimal backend frameworks for Node (and Python, and others) that can be and are used to build traditional "load a page for every interaction" applications, and Zod or something like it would be useful for those since minimal frameworks often don't include validation. Zod isn't exclusively for SPAs or even web applications. It's schema validation, which is useful in many domains.