This is an excellent answer and I wish I knew all of this when starting to use archlinux. “Arch does not support partial upgrades” is something you can read everywhere, but it’s rare to find such a good explanation of what exactly a partial upgrade is, and which commands lead to it.
I only learned about all of this when I got into some broken state by randomly running pacman commands.
Everyone, be like this guy. This guy explains stuff well. Newbies need stuff explained.
No kidding I wish I was paid for this instead of what I actually do at work.