In a backend where you need a heavy-duty, multithreaded process to handle long-lived computations, node is probably not the way to go unless you want to pay for all the extra instances you'd need for the same amount of load. In my experience, for example, a java-based graphQL server (that spawned multiple connections to various services) needed much much less in the way of resources than the node equivalent serving the same amount of traffic - AND the latencies were generally much better with the java server, depending on the size of the JSON payloads that it was handling.
All that being said, you can certainly architect your way out of that problem and I imagine a relatively small percentages of web applications even HAVE that problem.