I remember trying to spoil it, but snake already killed dumbolddoor, I mean how many more random moody professors going postal is going to be a surprise?
I still fondly remember when a new harry potter book was released in the aughts, trolls on SomethingAwful were spamming "snape kills dumbledore" everywhere and so the mods threatened bans for anyone who didn't use spoiler tags. Some clever troll posted [SPOILER]SNAPE KILLS DUMBLEDORE[/SPOILER] as a thread title, spoiler tags don't work in titles, mods left it up because why not.
when that book (half blood prince?) came out here in the uk, on day one people put big banners over a couple motorways with SNAPE KILLS DUMBLEDORE on them lol
they got early copies through a delivery truck crashing a week before iirc
There were a significant amount of people trying to spoil the game as some way to spite JK Rowling. It was spoiled for me online while my SO was playing it. Here's a Google search for you to browse with many articles and SM posts warning spoilers.
You might consider that you don't know everything that happens online, and just because you're unaware of something doesn't mean it didn't happen.