Arch is my distro of choice at the moment - but even it simply teaches how to copy/paste to make things work, never explaining what is happening when you run a command, or how it manages to do that.

How about Slackware? Personally I find it unjust how rarely Slack is mentioned nowadays compared to distros like Arch and Gentoo. From the conservative development, the BSD-style init system and minimalistic package management, I've always found it to be the most UNIX-like distro of all, and my personal choice.