alt Hacker Newsunless you own/write the whole software stack(not the web stack), i doubt anyone can fully explain their project.
For example, if in your project you have to write a file, and someone ask you how does the kernel cache file writting, that would not be an easy question.
You're missing the point and taking it to an extreme.
Let's say I write a toy project to log all sites I visit to a text file. The goal is to learn browser extensions, not learn kernel cache. There's a clear boundary, and anyone asking me about kernel cache would sound very weird. It's obviously a lot of layers of knowledge deep into the stuff I'm learning.
If my toy project is a beautiful web app, then CSS is _not_ several layers deep. It is in the front of it. It's a dependency I _need to learn_ in order to own my project.
If my toy project is a web app, and doesn't matter if it looks beautiful or not, then I want to spend my time away from CSS (either writing it by hand or interacting with an AI). I am fine with having it ugly.
Understanding these dependencies and layers of knowledge is part of the learning as well.
Again, this works for teams as well. There are certain things, at a certain level, that if you don't have someone in the team that knows it, leads to a precarious situation.
The fact that people don't recognize this, and mistake it for not made here syndrome and other nonsense, is actually scary. It means those recipes (don't reinvent the wheel, good is better than perfect, etc) became mantras that people repeat without actually understand why they exist, and those boundaries have become arbitrary and meaningless.