Spoilers definitely seem to be a big concern these days and not just with video games. Movies, books, TV shows, Anime, Cartoons, etc. Pretty much anything is fair game online though. I find it a bit odd that you'd avoid trailers, announcements, etc. yet you'd watch analysis videos. Seems a bit counter intuitive or redundant if you ask me but it's your choice at the end of the day. I'm kind of torn when it comes to this predicament/dilemma though...or at least with KH3. On one hand I REALLY want to see what new additions have been confirmed and yet on the other I don't want to spoil or ruin the experience at all if I can help it. It's insane how many trailers these days contain spoilers and it's really bad with video games and movie trailers. Seriously though the only solution I know is to either avoid them entirely if possible or straight up disconnect from the internet in the months or weeks leading up to the release. Go completely dark ya know? Personally though I don't think Nomura and the Square-Enix would intentionally spoil anything major. I mean hell Nomura has stated numerous times in various interviews throughout the years how he can't or won't talk about certain things because it's a spoiler or due to is sensitive nature. I really do hope that Sony releases that 2.8 demo on PSN some time prior to the games release. It looks really fun and while there are some obvious spoilers from what I've gathered anyways I still want to see how it feels, plays, looks, etc.
Thing with spoilers though is yeah it sucks to get things spoiled in advance, especially if you're highly anticipating w/e it is you're looking forward to, but I don't think it will ruin the overall experience or at least imho. George R.R. Martin had some really interesting points about spoilers and how even if you know what's going to happen at certain points that doesn't mean you still can't enjoy the experience. More about the journey and not the destination things along those lines really.