What? "Any node.js application" most definitely won't successfully run client-side. Similarly, "bash" most definitely won't run client-side. Additionally, most client-side frameworks don't effortlessly work in a DOMless environment.
> that could be run on either server or client, which is obviously meaningless
How is that meaningless? That's literally the entirety of what's important about isomorphic apps: the same codebase can be run client-side and server-side.