Why is NPM repository not among project repositories?

Multiplatform
1

When I add an NPM dependency to a project like this, I assume that the dependency must somehow be fetched from the NPM repository:

kotlin {
    sourceSets {
        getByName("jsMain") {
            dependencies {
                implementation(npm("my-npm-package", "1.0.0"))
            }
        }
    }
}

However, when I inspect the project’s repositories like this, the NPM repository is not present, only the repositories I have configured explicitly myself:

tasks.create("printRepositories") {
    dependsOn("build")
    group = "debugging"
    doLast {
        println("Repositories:")
        project.repositories.forEach {
            println("- ${it.name} (${it.javaClass.simpleName})")
        }
    }
}

Why?