I can understand the argument, since npm has no solution for TypeScript packages, unlike JSR:

"You publish TypeScript source, and JSR handles generating API docs, .d.ts files, and transpiling your code for cross-runtime compatibility."

Still would have been nice to have this for private packages.

This makes Deno/Bun much more attractive alternatives

JSR does that? Now that might be a good reason to move my packages over to get rid of tsup.