Most modern programmers don't learn COBOL60 or Commodore BASIC. Modern mathematician very rarely study writings of Euler or Gauss; even 50 years old math books may be hard to grasp for modern students.
I agree that using a simpler tool for educational purpose is useful, but since SysVinit is obsoleted almost everywhere, it made sense to drop it. LFS could have chosen a simpler init than the domain standard, like runit or s6-init.
See this GIANT argument with hundreds of comments? It seems some people believe that SysVinit is, in fact, not even close to obsolete.
If Gnome/KDE can't support the init system I choose to use, then I don't choose to use their garbage software anymore.