What's the right metric? Pre 1.0 typically means the software is still in beta. I realize node.js is used by many sites and large sites, but if it is stable/reliable the versioning should reflect that.
Can you expand on that any further? I can't tell what you are trying to say, because my comment was made in awareness of Semantic Versioning.
While I support a de facto standard around the meaning of version numbers, you must judge a project's version number by the versioning rules the development team communicates. By the Semantic Versioning Specification's own guidelines, Node.js should be at least at v1.0.0, but the developers have decided against it. Therefore, when judging the stability and maturity of Node.js by the version number alone, you can only compare it to previous releases of Node.js.
In the "Semantic Versioning Specification", it's seems inconsistent when you look at #4 and #5 and compare it to rule #1 at the top. Changes in x (x.y.z) should be reserved for "when you make incompatible API changes", but the #5 in the spec forces you to change x (to 1) even in some situations where there may not be "incompatible API changes".