I think Orson Scott Card, despite being a complete loon, raised an interesting concept in the book Speaker For The Dead. Obituaries should be spoken honestly to all. Not speaking ill of the dead is morally wrong.
You can't defend yourself when you're dead. You can't be your own witness. Nor can you face your own accuser. Also, who would you trust to speak that truth for you?
Also, grieving family members are not the most rational people. Doing this could trigger violence in practice.
And obituaries have a legal function. As a modern society, we want to encourage the publication of obituaries as soon as someone passes away. It mitigates the risk of potential fraud.
Maybe just me but I feel like this misses what Speaker For the Dead does. It isn't about speaking ill or not ill of people but understanding their life experience, to give context to who they were as a person. This moves past the superficial reading of a person that just listing their actions and classifying them as good or bad.
Obituaries tend not to.