conspiring to triage
There's a new crime. Let's commit it!
It certainly could. Code, markup, graphics, it's all copyrightable. Whether it has in the past or not isn't relevant at all since it's functionally the same as any other code. And yes, people borrow from each other all the time, but that doesn't make it legally sound.
and after saying "Ok, I got it", *guarantee*, that I can turn off the system in that very moment, without losing data or corrupting the file system in any way.
Which is precisely what fsync does, and is precisely what these developers didn't use. The filesystem knows better than you do how to get all the data it has to write onto the platters as fast as possible so if you need something specific like "it's important that this data get written now, so I'll wait for you to finish", you have to ask. Otherwise your apps would run a great deal slower since every little write (even a single byte!) would have to wait for the OS to say "OK, it's on disk". And if you really want that, there are flags you can use, e.g. O_SYNC. But you don't.
How can you work when the system's so crowded?