The "more difficult" in this quote makes me somewhat angry.
`This breaks down if JavaScript library authors are using languages that are different (and more difficult!) than JavaScript.`
JS is absolutely not easy!
It is not class oriented but uses funky prototypes, it has classes slapped on PHP-Style.
Types are bonkers, so someone bolted on TypeScript.
It has a dual wield footgun in the form of null/undefined, a repeat of the billion dollar mistake but twice!
The whole Javascript tooling and ecosystem is a giant mess with no fix in sight (hence all the rewrites).
The whole JavaScript ecosystem is ludicrously complicated with lots of opinions on everything.
Tooling is especially bad because you need a VM to run stuff (so lots of rewrites).
This is why Java never got much traction in that space too.
Go for example is way easier to learn than Javascript.
Here i mean to a level of proficiency which goes beyond making some buttons blink or load a bit of stuff from some database.
Tooling just works. There is no thought to spend on how to format stuff or which tool to use to run things.
And even somewhat difficult (and in my opinion useless) features like classes are a absent.
Want to do concurrency? Just to `go func whatever()`. Want it to communicate across threads? Use a channel it makes stuff go from A -> B.
Try this in JS you have to know concepts like Promises, WebWorkers and a VM which is not really multithreaded to begin with.