I think really what happens is Node enables a new type of stack[1]. It doesn't actually really step on anything new the SPA's aren't already doing. Instead it moves to become isomorphic, so initial render is done by Node, but still the data sources, validation, and heavy backend logic all stays behind an API. That API could certainly be Erlang powered.

Also to respond to your points...

1. This I see as the most valid argument, but not a deal-breaker (see Walmart, LinkedIn using Node without problems scaling).

2. Check out Flow by Facebook [2] or TypeScript.

3. Not true with require/modules.

4. It's incredibly easy to include a JSLint file in your repo and as a git hook.

[1] http://nerds.airbnb.com/isomorphic-javascript-future-web-app... [2] http://flowtype.org/