Wow, I feel like I could have written this. Back when I used Python, I had a folder full of functions I would copy-paste between my projects. (And maybe some of the projects contained unit-tests for the function. I didn't always keep those tests in sync.) Updating them was a pain because inevitably each one would get slightly modified over time in each project separately. Eventually, I bundled all of them into a bundle of completely unrelated utility functions in a folder on my computer somewhere, and I would import the folder with an absolute path. Sharing the code I wrote was a pain because of how much it referenced files on my local computer outside of the project. I never considered publishing my utility module because all of the stuff was completely unrelated. I'd rather publish nothing than a horrifying random amalgram that no single project of mine was even related to all of the subject matter present in it.

With npm and the popularity of small modules, it was obvious that I could just cheaply publish each of my utility functions as separate modules. Some of them are about a few dozen lines, but have hundreds of lines of tests and have had significant bugfixes that I am very happy that I haven't had to manually port to dozens of projects. I don't miss copy-pasting code across projects, no matter how many claim I've "forgotten how to program".

What I see is that a module has a non-zero overhead in complexity in itself. That is, ten 10 line modules and twenty 5 line modules do not yield the same complexity. The modules themselves have a complexity overhead associated, and submodules have their own complexity overhead associated, albeit smaller than first party modules. That complexity is easily seen from the recent situation of unpublishing modules, which resulting in modules multiple steps removed having problems building.

So, when I read "It doesn't matter if the module is one line or hundreds." I call bullshit. There is overhead, it's usually just fairly small (at may event begin to rival the gains from using a module at that level), but that small amount adds up. Once you've had to deal with a dependency graph that's 10 levels deep and contains hundreds or thousands of modules, that small extra complexity imposed by using a module is no longer in total, and comes at a real cost, as we've just seen.

Other module ecosystems have gone through some of the same problems. There was a movement in Perl/CPAN a few years back to supply smaller, more tightly focused modules a while back, to combat the sprawling dependencies that were popping up. The module names were generally suffixed with "Tiny"[1] and the goals where multiple:

- Where possible, clean up APIs where consensus had generally been built over what the most convenient usage idioms were.

- Try to eliminate or reduce non-core dependencies where possible.

- Try to keep the modules themselves and their scope fairly small.

- Remove features in comparison to the "everything included" competitor modules.

This has yielded quite a few very useful and strong modules that are commonly includes in any project. They aren't always tiny, but they attack their problem space efficiently and concisely. Even so, I'm not sure there's ever a module that's a single line of code (or less than 10, given the required statements to namespace, etc), as the point is to serve a problem, not an action.

1: https://metacpan.org/search?size=20&q=%3A%3Atiny&search_type...