Because sometimes, we just don’t wanna hear ’em.
(and *spoiler warning, just in case)
The subject of whether or not spoilers ruin the viewing experience is very debatable, yes, but I think it’s in good taste to at the least respect the fact that some people do in fact think that being spoiled lessens the enjoyment for certain anime/manga (or, any media for that matter).
My personal stand on the topic; it won’t mess with my watching, but more often than not, I’d prefer to be in the dark (unless I absolutely cave-in, then everything’s fair game by that point, lol). Which is why, I believe there should be some sort of delicate handling when it comes to spoilers.
For example (and I think people have already come to terms with this unknowingly), there do exist widely accepted and known spoilers. A huge bulk (if not all) of these choice scenes consist of popular death scenes (you should know by now what I’m talking about). If you’re someone who frequents the anime/manga side of the ‘Net, then it becomes virtually impossible that you won’t encounter at least one of these revelations. No one is to blame for this, really (and hey, these supposed “universally” spoiled shows are considered some of the best of all time)
In regards to concealed plot occurrences or twists then, well, that’s where I think most of the problem lies. Sometimes people wanna know the answer right away, sometimes people savor the moments of ambiguity. Whether it’s the former or the latter, I think I can empathize. It’s all very situational; like, maybe, a show’s been dragging it’s plot heels long enough and you find yourself needing an incentive to watch a show ; or the arc is finally coming to fruition with the big reveal of some not-yet-known character’s true identity.
I find it best to just keep it inside until you’re asked (or if you really really have to, pre-empt it with a “spoiler alert” or any variant you may prefer to use); and on the flip-side of that, say when you don’t want to be spoiled. This stuff happens inadvertently. I know, it’s happened to me before. This is by far not a sure-fire way of handling it (it still happens to me now, lol) but think of it as a way of minimizing casualties. Some bits and pieces of plot might slip through, but at least you’d be left with something. I mean, unless of course, your friend just blasts you with everything, and by that point you might as well just look at the bright side (hey, no more guessing next ep!) and enjoy the show.
Finally, knowing that you can potentially spoil yourself if you go ahead and dig deep enough is a nice thing to keep in mind. “Curiosity killed the cat”, as they say.