The thing about that enemy type is it was publicly shown constantly in publisher-backed official videos. What constitutes as a spoiler for someone will be wildly different as someone may have intentionally gone on a blackout while some other guy only watches every official trailer and talks about things shown in it.
I agree that a lot of stuff should be spoilered, but expecting 100% of the people that post about how much they liked a chapter with a post like "chapter 10 was
" or something that feels like a minor thing to someone isn't really gonna happen, since most people wouldn't even have it in the back of their mind that it's a spoiler at all. But, it is true that seeing a constant flow of people thinking certain chapters are great will set an expectation if you're not there yet, but that's just a natural part of a discussion forum where a lot of people contributing to a topic and some move through a game much faster than others. It's also a no-win scenario at times, like the Tales of Xillia 2 thread had some people actually complaining that the entire thread page by page was basically loaded with black bars and that people should move to the spoiler thread, but the discussion was about something mid-late game and obviously you can't just randomly go into a thread that's open season mostly focused on endings and try to discuss something while trying to dodge endgame spoilers
Something that seems more obvious as a blanket obvious example would be not to post an embedded image of the actual post results screen since the game visually shows bosses/monsters since I saw that happen and probably have a good idea on what the final boss looks like based on it. Or people that just post an entire post coated in black so you start to unravel it at the start to see if there's context and it's just randomly talking about some final level shit out of nowhere.