1) Local servers are a no-go for multiuser environments unless you want to log-on every time you run your "native" app, as most (all?) browsers don't support http over domain sockets and there is no authentication for local sockets.
2) Managing the health of the service properly in a cross-platform manner is complicated. With electron if the app crashes, it just crashes. With a local server the browser tab just stops working. Sure technical users can figure it out, but if you are targeting a gui over a console, presumably you are trying to capture some fraction of non-technical users.