This, and package managers.

For example, node.js, many people say its popular because lots or webdevs knew JS already, but that's not even close to true, most people went to node.js because they found a couple of usable libraries on npm that gave the trust necessary to start the project.

You got it reverse, since when Node started getting adoption npm wasn't even a thing or was still small. Back in the Node early days it was all "we can run JS we know on the server now" (plus some cargo cult hype about it being "fast because async").