Otherwise, it can be cut off.
It is fair - good posts were considered meritorious by people who didnt have enough smerits. Therefore these posts were not merited.
But then imagine the following scenario:
Many people are rightfully given merit by someone whose post is later deleted. Then those people suddenly rank down. And in fact, what if someone had a highly merited post that was deleted? If that individual had given merit to many people, that's a lot of lost merit from the chain.
You have to consider all these edge cases. :/