it uses a lot of infrastructure that node doesn't have, like Request objects and Response objects and Body objects and mime checking etc etc list goes on.

if someone feels like adding all those things to node and feels like arguing with our core maintainers about the duplication with http then maybe it will be added.

https://github.com/nodejs/node/issues/19393

Because Node.js already provides low level network access, while in browsers fetch() is the (second) lowest abstraction you can get to.