1) Actually I get tons of people asking, but as you said, "friendless sacks of shit" don't not know that. It's ok. No harm, no foul. In fact, of all the spoilers that I have posted and commentary on LN, WN, manga differences and such, this might be the ONLY time someone has whined. Seriously, one complaint. With hundreds, literally hundreds of thank yous. I don't drop massive bombs, or even details, unless specifically requested. Any moron could see where this story is going. Plus, harem tag, buddy. Reading, neat, huh?
2) Spoiler tagging something implies....that it could be a spoiler. This is why I put it behind that specific tag, instead of in bold, italics, in quotes, or with a big foam finger. Then, for the absolutely braindead (again, your words) I put a warning ahead of that. Neat, huh?
3) As to my motivations: OP was concerned about future shitty characters ruining the manga. If you were driving along, and didn't see the "CLIFF AHEAD! STOP" sign, and I pointed it out to you, would you really be upset that I saved you time, energy, 1100 chapters of rental girlfriend, death, etc? Or would you rather drive off? Either way, doesn't actually matter to me. It's rhetorical.
Oh, and goading you along is pretty fun. Let's do this again sometime, maybe with less name-calling. Cheers.