That’s a lovely comment, thank you. If you’re keen to think about it more, consider the fact that the existing members of the project that’s being late are actually in not as much of an advantage compared to the new joiners, as it’s common to think.

Yes, they know how the feature they work on relates to other features, but actually implementing that feature is very often mostly involves fighting with technology, wrangling the entire stack into the shape you need.

In Brooks’s times the stack was paper-thin, almost nonexistent. In modern times it’s not, and adding someone who knows the technology, but doesn’t have the domain knowledge related to your feature still helps you. It doesn’t slow you down.

One may argue that I’m again pointing to the difference between accidental and incidental complexity, and my argument is essentially “accidental complexity takes over”, but accidental complexity actually does influence your feature too, by defining what’s possible and what’s not.

Some good thoughts (not mine) on the modern boundary between accidental and incidental complexity: https://danluu.com/essential-complexity/

I sort of agree that the surface area and incidental complexity of stacks give more space to plug more developers in than was true in the 70s and 80s. But I disagree strongly this invalidates Brooks Law. Certainly there are cases where adding people helps, especially if they are stronger engineers than the ones that are already there, but I’ve also seen way too many projects devolve into resourcing conversations when the real problem was over-complicated, poorly reasoned requirements, boil-the-ocean solutions promising a perfect end state without a clear plan to get there iteratively.