How is this best? It defeats the whole point. I’m going to stop recommending LFS to people wanting to learn about this stuff.

Learn about what stuff? Linux? System V UNIX?

I haven't done LFS since my tweens (and I'm almost 30 now), but I remember the sysvinit portion amounted to, past building and installing the init binary, downloading and extracting a bunch of shell scripts into the target directory and following some instructions for creating the right symlinks.

Obviously, you can go and check out the init scripts (or any other individual part of LFS) as closely as you wish, and it is easier to "see" than systemd. But I strongly protest that sysvinit is either "Linux" (in that it constitutes a critical part of "understanding Linux" nor that it's really that understandable.

But setting aside all of that, and even setting aside the practical reasons given (maintenance burden), when the majority of "Linux" in the wild is based on systemd, if one wanted to do "Linux From Scratch" and get an idea of how an OS like Debian or Fedora works, you would want to build and install systemd from source.