Answer:
Probably because that requires them to get into the cemetery with the body, dig a hole, put the body in the hole, bury the body, and leave the cemetery unnoticed. Depending on if the cemetery has a gate it requires the murderer to throw the body over the fence then hop the fence himself then bury it.
Butttt, there are records of people in the cemetery of which who died, so if someone notices that there is a hidden body, but on the records there is no record of that person then an investigation is gonna start anyway. Plus a family member has got to notice that someone is missing.
Odd question but fun to answer lol