The only thing i'd add is that most multiplayer games have this inherent downside; players are trying to 'play' each other, and sometimes, that leads to people taking "who's taking who's side" a bit too seriously, or that they just feel like it's kingmaking. It's the nature of the beast unfortunately.
One more thing i'd add is that things that are secret in-game (your hand, contents of your library, and so on) should be kept so. It means that other players are then much less likely to be able to "tell you what you should do". It's your game, and it should be you who's playing it. AFTER the game, it might be worth looking over some misplays and whatnot, but during the game, what your opponents tell you about how you should be playing should be kept to a respectful level.
Ive made this sorta mistake many times in the past, and it's worth repeating for y'all who have a hard time with it. I don't recall the exact situation now, but there were times when the table knew that a player had removal for a particular problem for the table, but wouldn't remove it. Myself and the other player were pretty annoyed about it, and kept hounding the player with removal. one or two rounds later, the player with the removal not only killed off the problem player (with the problematic permanent as a synergy piece or aikido-piece), but severely crippled the other two, and pushing himself waaaay up into the lead. That was something that the player planned, and regardless whether or not the other players thought removing that permanent was a good idea, it certainly was the correct play for the player with removal to not use it.
Use the hidden zones!