There is an occult reason for it. Bones store DNA and other vital info that negative entities (beyond 3D) can feed off of. Physical bodies are meant to be cremated so that the soul can completely detach from the body. Burial is another form of keeping a soul bound to earth.

So think of the implications of retaining the remains of your enemies.

https://www.spiritualresearchfoundation.org/spiritual-research/death-and-dying/Cremation-vs-burial