Your operating system is concurrent even if it's single threaded.
Concurrency is about doing things in the same time period not necessarily at the exact same time.
Concurrency is about doing things in the same time period not necessarily at the exact same time.
If you introduce blocking into an application then to the user it slower, but in terms of computation it could still be faster by some magnitude.
It's like having C block on a network call while having in-browser Javascript concurrently move past it and declaring Javascript faster.
Actually, comparing runtime/platform (Node) to language is completely pointless. Language is, well, only a language, it can't be "faster" or "slower" unless we're talking about coding speed. We have to compare implementations.
And even if we treat Java as a platform, contrary to Node it has ton of highly-varying implementations, so it's still pointless without careful clarifying what one compares. Or they may accidentally find out there's a Java variation with green threads somewhere that may break the whole "look, their ugly threads are slow and our event loops are fast" charm.
The article is just a pure load of non-sense. Highly flammable, though.