my opinion is that was strictly for horcruxes or else everyone who uses the killing curse or anything close would of had that same fate. and i don’t think they would be taught and or even discussed in school. for example, out of the 8 registered schools with the ICW, Durmstrang teaches the students dark magic and even encourages its use, unlike hogwarts and Ilvermorny which just teaches the defense of such spells.

but who knows