I'm sorry that you don't see it and I don't think I'll be able to persuade you.
Perhaps you might take into consideration the Jewish concept that the only pure "mitzvah" (pretty much, but not exactly a "good deed") is that of throwing soil onto the grave. There is no possibility of the deed being repaid. Every other mitzvah carries with it the possibility of reciprocation or recognition.
There's no escaping the system. I could say that if you fill up and tend my grandpa's grave, I'll fill up and tend yours.