Comments like “it’s standard” do not answer the original question:
“I'm curious why Node core has decided to make this an official part of Node?”
The standard describes many functions and classes. What makes fetch more land-able than e.g. the event system, of which node has incompatible implementation? Or feature detection via navigator. Why it? What were the main point(s) of adding fetch specifically?
If something is standard, and it makes sense in the context of a backend, then it's convenient to just use the same API on both ends. Navigator makes almost no sense on the backend unless maybe it worked as a dummy polyfill object.
