Comment by SoftTalker

In the modern era it's usually said because the dead person cannot defend himself.

Now, Adams had plenty of opportunities to defend/explain his comments on certain issues, and he did not satisfy many people with those or perhaps dug himself in deeper (I myself really only know him from Dilbert in the 1990s, and am only superficially aware of anything controversial he did/said outside of that).

But I don't see anyone saying anything about him now that was not being said when he was alive.