node.js – Why doesn’t it use all available RAM?

I understand that Node.js applications are often scaled using multiple processes, containers, or servers.

However, I’m trying to understand the reasoning behind the default V8 heap limits.

For example, if I have a server with 32 GB or 64 GB RAM, but a single Node.js process can only use around 4 GB of heap by default, doesn’t that leave a large amount of memory unused?

Why isn’t it common to run a single Node.js process with access to most of the server’s memory? Is it mainly due to garbage collection performance, reliability, or some other reason?

How do other runtimes such as Java, Go, or .NET handle this? Do they also impose practical per-process memory limits, or can a single application process efficiently use tens of gigabytes of RAM?

I’m trying to understand whether this is primarily a V8 design decision or a general principle in large-scale server applications.