I think the linked resources show that it probably never worked the way we hoped it would. The first investigation I linked was from 2011, prior to the existence of webpack.
A lot of people have high-hopes that import-maps[1] will allow us to consume a variety of ES Modules from a variety of CDNs effectively. It gives us back the "bare specifies" that CommonJS introduced, where you say `import $ from "jquery/index.js"` in the code you write. Then the import-map helps the browser understand which CDN or otherwise to reach out to get that index.js file. We think this will allow ES Modules to be broadly usable & "modular", in a way that they have not been. I & a bunch of others are holding our breath on this one. It feels like it really can fix this huge hang up, giving us a way to author modules in a way that allows modular consumption.
[1] https://wicg.github.io/import-maps/