If your claim is that it's impossible to contribute to a package written in TS without writing TS, even if the authors publish a JS version to NPM, I completely

If your claim is that it's impossible to contribute to a package written in TS without writing TS, even if the authors publish a JS version to NPM, I completely agree. I also agree that this creates a divide between authors who write TS/publish JS, and those who write JS directly.