Those libraries/languages don't have the user install base of javascript, which is nearly every single piece of computing that has been released in the last 10

Those libraries/languages don't have the user install base of javascript, which is nearly every single piece of computing that has been released in the last 10 years, albeit most of those older models probably won't be able to run the javascript that's running now. And there is no "click download" required like those two libraries would need and also no need for patch updates. Your "download" is just pointing to a URL.