[crdrost]

Also people routinely use other single threaded things for the web, notably Python and Ruby have global interpreter locks and PHP has also usually been multithreaded only by being multi-process (you have to add pthreads on I think?).

Multithreading is a nice to have; it has a bunch of costs around needing to introduce locking and synchronization primitives into the language, those costs aren't the worst thing ever but it's often nice to not have to deal with them.

[zelphirkalt]

I think you are mixing up lots of stuff or at least write about them in a misleading way.

Python has async, has green threads, and has OS threads through the multiprocessing module. The fact that it has the GIL does not mean, that it cannot use OS threads or multiple processes. JavaScript in comparison does not have multithreading. NodeJS itself is multithreaded, but you cannot put application computation on those threads. You will need to use worker-threads and basically like PHP run multiple instances.

However, neither of those languages is particularly nice for using the multiple cores available in modern machines anyway.