Earlier quoted context omitted.
Why would you use something other than a JS framework to build a web app back-end? You don't have to deal with OpenAPI or GraphQL, you can just use server actions.
Better/scalable performance, actual runtime type checking without wrapping everything with third-party libraries and paying the associated overhead, talent pool in my area, better (or even existing) libraries for the task at hand, better observability instrumentation, personal preference... is this really an honest question?
Yes, there is nothing that works better than server actions. None of what you listed really makes sense to me. I have never had any runtime performance problems with TypeScript and wasn't JavaScript the most popular programming language in the world (the talent pool argument)?.