What's even worse is destruction by the publisher of the campaign base that the PC's very well could have succeeded in saving . . .
What I have in mind is the 2E version of Greyhawk, "From the Ashes", in which it was assumed the Giants of G123 succeeded in conquering and massacring Sterich and Geoff. Our party killed Lloth and WON the war to save our homelands -- took us two years of gaming, but we did it, the last mission before we retired our few surviving characters and broke up as a gaming group. I'm still pissed at TSR 13 years later for saying we failed. Orc-heads!
Lesson: Never, ever "update" a campaign setting.