Why not make students reproduce work?
A chapter that does that is fine; I had one in my thesis. It can for example serve to set the stage for your original work. But someone with a PhD has to be able to do more than just repeat the work done by others, and the thesis has to show that capability. Replications are valuable, but a thesis consisting solely of replications won't show what it needs to show.

Instead we should try to find a way to make replications publishable (especially if they show what is already known) and worthwhile for established authors, rather than diminishing its value by delegating it to students.