I agree that going out of your way to spoil something is a dick move.

But I feel like there needs to be a point where the burden of avoiding spoilers falls on the person who doesn't want something they haven't seen to be spoiled.

Like if I post an article or thread about Fight Club now, I shouldn't have to flag spoilers - if you're clicking then you probably know the movie and are coming for discussion about it, and should expect that spoilers might be unflagged.

On the other hand, it's reasonable that discussion around a movie like Knock at the Cabin should still have spoiler tags, because people are coming to articles and threads looking for opinions on whether the movie is worth seeing, not plot discussion.