No, they're right. It sounds like you're inexperienced with the tooling and should spend some more time with it. That's not even a criticism, just a truth.

Take this:

> These things typically produce tens of thousands of lines just to add simple libraries.

If you're ending up with a bundle that's thousands of lines long, you've done something wrong. My team use esbuild to bundle code for AWS Lambdas and usually end up with minified code under a couple of kilobytes (though admittedly the bulkier stuff sits in a Lambda layer - since, you know, bundling everything under the sun would be stupid).