It kind of confuses me when I see people talking about cavaliers as if the Nine Houses have established and normalised some radical social role of human sacrifice. It really doesn’t seem to me like the role of a cavalier is that simple. The only members of their society we’ve seen who weren’t horrified by the idea were the Tridentarii.
The career soldier, who was born into the military class and trained for that role since birth, believes no necromancer should ever have to see their cavalier die. The other child soldier was killed while putting himself between his cavalier and danger. The heirophant of the Emperor’s law who draws on his cavalier like a battery—a level of exploitation the other Houses condemn—turns against the will of his God when he witnesses the sacrifice expected for lyctorhood.
The deliberate sacrifice of a cavalier is not normalised. Not even in the front lines of their military. The role of a cavalier is exploitative, of course, and that’s where the interesting part begins. Is it any more exploitative than a king whose knights are trained to die in battle? Than employees who are forced to work or starve? Than the existence of a noble class, or capitalism?
Human suffering exists in any society, and in most societies I know of, much of that suffering we inflict on one another through exploitation. The Nine Houses are not unique in this respect. I am very much in awe of the worldbuilding in this series, tho, that it has managed to defamiliarise human suffering and class dynamics as to show us their grotesquerie plainly without ever tipping over into anything as straight forward as direct allegory.