The secret assumption is that things will break and the builder will learn how things might break and how to fix them.

I've had a lot of fun with LFS, but if everything goes smoothly it is a bit pointless. When builds broke or I missed components there was an opportunity to better my understanding of the system. Experience with multiple failure modes in a safe environment - it counts for a lot.

It also forces you to learn what the dependency graph looks like and a little bit of why, which can be helpful.