Node.js brings callback hell to the serverside world of threads and we're supposed to be grateful? It's like you don't know the history of computing. Callback-based code was the original programming model in UNIX dating back decades! Threaded code came about because it's far easier to write it than callback-based code.

The ONLY reason to do callback-based code is for performance reasons: for network-IO-heavy apps there is less OS-level overhead from managing thousands of connections with a few threads using the OS-provided non-blocking I/O operations than managing a connection per thread. Even then, if you actually want to do better than connection-per-thread, you have to avoid the POSIX API for non-blocking I/O and use whatever OS-specific API is available for better performance (epoll, kqueue, or completion ports).

The greatest joke of all though is that Node.js is dirt slow because Javascript is dirt-slow. Yes, you may be able to invent some microbenchmark where Node.js looks good, but the only reason it does in that benchmark is because the Node.js app is spending 99.9% of it's time executing code in a C library. Any real-world Node.js app is going to be slow because Javascript in general, even on V8, is anywhere from 10-100x slower than C or even well-written Java.

And worst of all, Node.js is single-threaded! If you want to scale onto all your cores you have to go multi-process, which is an incredible pain in the general case. So, you switch to a runtime and framework that forces a more difficult way of programming on you (callback hell) but which is better for general networking performance, but you use a dirt-slow, single-threaded runtime while doing so. You are basically ending up with the worst of both worlds, and any decent development team will run circles around you in performance and productivity with just about any other backend stack.