Minimal yes, unmaintainable maybe, but insecure? Really depends on your threat model; courtesy of "minimal", there's not much attack surface to go around.

> Only think it will teach you is why distros and package managers exist.

And more importantly, how a distro works and what a package manager (and package build process) has to do. LFS isn't a terribly practical output for many people, but building it is a good learning experience regardless of if/how you use the built system.