Or people could just not write shit code. No idea why expecting basic competency with the language you're using is so out of vogue these days.

Reading one of your dependencies to track down a bug, and finding that they've written it using a totally alien subset of the language that you don't use, is not a lot of fun. The JavaScript community in particular both loves dependencies and loves experimenting with subsets of the language, when they're not embracing libraries that let them shift wholly into idioms from some other language. So as fun as it might be to write in some language that had these from the start, I'm not thrilled about giving folks a dozenth way to accomplish the same thing.