My background was doing low level C++ in HFT/Algorithmic trading for years, with a bit of Java interspersed, before doing this whole complete right turn of doing webdev in js for ecommerce. In C++, doing web stuff was very difficult, build times were long, JSON support existed but was awkward, iterating was just very difficult, even when you had your whole build/deploy setup going, there was still a lot of work if you wanted to build a CRUD app just marshalling and unmarshalling objects to the DB, etc. It was a drag at best and a real pain at worst. Java... was a bit better, and I don't really have a problem with Java as a language. Java programmers, however, seem to really delight in building architectural monuments and get paid by the abstraction. In every java system I have jumped into, you are always neck deep in xml, and massive object hierarchies and factory factories and its just like where the F is the code that actually does stuff?! I remember working on one project, where I was building the "engine" and another guy was building the web interface for it, and was using Spring when it was relatively new, and he happily declared "all I need to do is wire up my configs now, I am pretty much done." Narrator: A week later, he still wasn't done... and this wasn't unusual in my experience, in most java apps "config" was just as complex and problematic as code, and the mindset of "its just config" made config changes more likely to cause a production outage of some sort.
Then, you take a look at node. You look at a getting started tutorial. Its javascript on the front, and on the back. The JSON in between is "native" and is convenient and easy to use, easy to read, lightweight, and just makes a lot of intuitive sense- especially when I had found myself neck deep in XML in previous jobs for the same tasks. I had a nice looking HTML5 web app running in a few minutes- my mind was blown. Then you take a look at the frameworks- express and hapi, and the vast module ecosystem- and how easy it was to build a simple CRUD website with leveldb, or mysql, or really an endless array of storage options. And people were using those options! It wasn't just the bog standard RDBMS being used every place, with your only real choice being mysql, postgres, or if you had money, Oracle. Building endpoints with routes in these frameworks made your code so easy to divide up along clear lines, and there just wasn't the endless miles of boilerplate/scaffold code, and ugly syntax and type systems to fight with and plan ahead of. Things Just Worked. Turning around a code change was a matter of seconds, not a minutes long build process- I had never felt so productive- and writing code was fun again! Deploys were easy, restarts were fast. Rollbacks, when necessary, were painless. There was a plugin/module for everything (too much in hindsight).
Now, this was 6 years ago. Go was around, but still kind of a blip on the radar, Ruby/Python were probably the closest real contenders. Ruby had lost steam, I honestly took some cursory looks at it, but it didn't seem to have traction. Python, suffered from its single threadedness and GIL, and its popularity with the ML crowd- Flask and such existed, but was pretty rudimentary compared to what Express/Hapi were offering, and no one seemed that interested in those projects. I like Go a lot, and for a pure backend service, it might be my go-to today, as one of the original arguments for Node was "its the same language on the front and the back, no more delineation between FE and BE developers, anyone can jump in and fix the bugs!" Which, along the lines of my original comment, don't really work out in reality, at least not on larger systems. People drawn to FE work usually have never done real systems development and don't understand how things work under the hood- which isn't a problem, until one day it is and then its a huge one.
The dynamic typing argument... is somewhat valid, but I found that enforcing api contracts with hapi/joi gave you the equivalence of type safety at your interface borders, while still giving you the flexibility of dynamic typing within your code. In fact, Joi went even farther than just type checking, it could check that your int was within range for the field, that your dates were formatted properly, etc... In mega large codebases, this will come back to bite you, but I found the plugin architecture of Hapi really discouraged that kind of crap from leaking in and it was easy to build truly modularized code.
The performance ceilings aren't that different, and not that impactful, at least not until you get to FANG scale, and I mean literally only FANG scale. We were running a billion dollar business with on 8 fairly small VMs for the API layer, which handled all of the ecommerce transaction handling. I remember at one point we encountered a memory leak of some sort in node, and the instances were falling over and dying about once an hour, but restarting and recovering- this was causing a few % error rates to our customers. I was insistent that we get all hands on deck to figure this out ASAP, and our head of Ops type person said "kevstev, we can throw hardware at this problem to meet SLOs until you get it under control. Your monthly server costs are less than my studio apartment cost me per month in Jersey City 15 years ago."
You just have to have a basic understanding of whats going on at an architectural level, something a few hours of doing the right reading and experimenting can get you if you have the proper background. The number of gotchas to avoid to get that performance were an order of magnitude, if not more, fewer than in a language like C++ (Which I feel has actually gotten so complicated and difficult to grok its become a parody of itself- and I say that as someone who used it and adored it for 15 years).