You know well that was planned so Napoli can rest after tough CL match they 3days before Juve's game.
Regardless, the decision was made well in advance. And the moment they made the decision, weather conditions were terrible, stadium parking lot flooded, just like many of the access roads. Weather was not expected to improve all that much. Deny it all you want, it is a fact.
But it turned out differently, because when kick off time arrived that day (even hours earlier already), the weather had changed & conditions were perfectly fine again.
What they did in Parma was the exact opposite, they knew about the weather conditions & expectations but still waited as long as possible. But of course, conditions could have improved (like the Napoli game).
Still, it's not sensible to call off games 30 minutes in advance (unless there's absolutely no alternative) when you know in advance that there's a possible issue. Key word being possible. As in maybe, and maybe not.
You need to think about both travelling team(s) & fans first, at all times.
Obviously, opinions of fans who regularly attend games (regardless of where even) & those who mostly/only watch them on tv will differ in this scenario.
You call off Napoli well in advance, nobody needs to go to the trouble of travelling, no one needs to risk possible flooding, etc.
You call off Parma less than an hour in advance, everyone is already travelling to the stadium, etc.
And I'm not saying there weren't any other motives at play for the Napoli game back then, far from it. But the way that decision was made & communicated was a hell of a lot better than what we saw last Tuesday.