For me something like a black banner signifies a tragedy, not merely a death. A bunch of children being shot, a war, a disease ravaging a country, etc.
I’m curious to learn others’ perspectives however.
It can be "kind of a best case scenario" and yet you still mourn the loss. Mourning doesn't require a tragedy.
My grandmother died in her sleep at 94, pretty healthy all things considered (still had a good head, could putter along, and was in her own home of more than 60 years), after having had a great day. Pretty much the best death she and we could have hoped for. I still wouldn't have minded having her nearby for a few more years.
So as it apparently does need to be said: we're humans -- we mourn our dead. That is, the black bar denotes death, not tragedy; when we mourn those like Wirth who lived a full life, we can at once take solace in the fullness of a life lived and mourn that life is finite. The death rite allows us to reflect on the finiteness of our own lives, and the impact that Wirth had us, and the impact that we have on others. You are presumably too young to have felt this personal impact, but I assure you that many are brought back to their own earliest exposure to computing -- for many of us, was Pascal.
Again, RIP Nik Wirth; thank you for giving so many of us so much.
and a black ribon signifies a great loss, not a tragedy.
Niklaus Wirth contributed quite a bit to our field, and, directly or indirectly, impacted many of the people who frequent this (programming technology oriented) site.