PostingWithPSP

Even if that's a quote from the site, I still think it's just trying to explain what React is doing in a more digestible way. Any state belongs to one component. The extend of any "propagation" is invoking some function you've been given by your parent.

What do you mean? Child components don't pass their state to parent components. It's what allows React to be declarative. It's right on the front page:

"React implements one-way reactive data flow which reduces boilerplate and is easier to reason about than traditional data binding."

Bad analogy. Treating your /etc/motd as a scratch space is a perfectly reasonable thing to do. It's not the difference between shitting in a toilet and a hole in the ground.

I understand the argument against editing a file in /etc for something only one user is concerned about, but I've been the sole user of every computer I've had, so this doesn't matter to me. I think that's the case for a lot of people.

The other arguments seem to be preference. Some people work better with paper. Some people only want system configuration in /etc. If you're a stickler for the Single Responsibility Principle in the config files in your OS, then I assume you already have your own solution to this problem and you don't need a tutorial from me.