Linux has always had an app marketplace, it just wasn't called a "marketplace" (when everything is free, the marketplace/store analogy isn't appropriate). At least in Debian and derivatives, everything is a one-click install since '98.
How JavaScript fits in this picture, however, is still beyond me.
an app marketplace is not simply about package managers. Its about an ecosystem that allows developers to develop high quality apps. Additionally its about payment systems, etc - but tgats not relevant fof this discussion.
I'm finding it hard to believe that you can woo quality desktop app developers using javascript.
How JavaScript fits in this picture, however, is still beyond me.