"The more powerful the language, the easier the libraries are to use." for anyone thinking of reading the title without the body
It's true, you couldn't really do Express in Java, at least not back then.
See C#'s asp.net core minimal apis (a express clone). So it is definitely possible but you need to co-develop the language. I think as you point out.
It’s possible to have something like Express, take a look at Javalin.
But Java problem is not the mechanics, it’s that the community doesn’t want nice things.
I don't understand, what's Express? As for libraries and Java, I'd argue Java became a well established enterprise language and platform exactly because it makes such highly effective use of libraries.