What did I learn from Linux from Scratch?
Which basic programs make up a GNU/Linux system
Where each basic program comes from
Each program's basic function
How it's built
How to configure it
How the programs depend on one another
I also learned that it is a lot of work to build a Linux distro from scratch, even the very minimal LFS system.
Note: You'll also have to read BLFS (Beyond Linux from Scratch) if you want a system that is actually useful as a desktop, server, or whatever. Luckily, BLFS continues where LFS left off, so you won't have to start over.
But the LFS book does assume a certain level of existing Linux knowledge. It says at minimum, "you should already have the ability to use the command line (shell) to copy or move files and directories, list directory and file contents, and change the current directory. It is also expected that you have a reasonable knowledge of using and installing Linux software."http://www.linuxfromscratch.org/lfs/vie ... sites.html
If you don't meet these requirements, you might want to use Linux a little longer before trying LFS.
Maybe give a distro like Slackware or Arch Linux a try; you can learn a lot from them, too.
Slackware and Arch aren't usually considered 'beginner-friendly" distros, but a beginner can use them as long as they're willing to learn and read the documentation.