IIRC it might have something to do with "Body Memory". The blood is said to have the essence of life within it so perhaps it's to avoid altering an individual.
en.wikipedia.org
There is A LOT that humans don’t know about blood. But we know enough because Jehovah has told us how he views it and what to do with it when a person or animals bleeds.
Deuteronomy 12:23-25: “Just be
firmly resolved not to eat the blood, because
the blood is the life, and you must not eat the life with the flesh. You must not eat it.
You should pour it out on the ground like water. You must not eat it, so that it may go well with you and your children after you,
because you are doing what is right in Jehovah’s eyes”.
Acts 15:28-29: “For the
holy spirit and we ourselves have favored adding no further burden to you except
these necessary things: to
keep abstaining from things sacrificed to idols,
from blood, from what is strangled, and from sexual immorality. If you carefully keep yourselves from these things, you will prosper. Good health to you!”