NPM does not make it any easier to glue stuff together, we have had packaging for decades. Just because you can pull in a package does not make it easy to work with the api in a standardized way.
I think the argument is Node.js projects are often stitched together from many packages with different APIs and are therefore a good example for stitched together programs that work.
The argument isn't very good in my opinion. Combining independent services differs from combining libraries.
