I was playing a game of Dominion (as usual), and I was wondering. Is there EVER a time where you would choose to not reveal a Province when someone plays a Tournament?
The classic reason is, it's a multiplayer game, and someone else already revealed a Province, hooray. You'd just as soon not give more information to in-between players.
Is there a time when the fact that you are presented with the option of revealing a Moat, or Trader, or Secret Chamber, etc. that would give your opponent a practical advantage? Like if my opponent has done Scrying Pool + Noble Brigand a couple times already and I would rather him think I didn't have a Secret Chamber so that he would leave my Gold on top of my deck.
Sure, I want to let an attack hit me (e.g. Margrave and I'm holding 3 greens) if my opponent knows that I have Moat, then they should only play attacks that will provide some direct benefit to them (e.g. Witch yes, Hag no) and they should rerank their card preferences (e.g. they are trying to draw deck and they have a Witch or another Margrave, they almost certainly want to prioritize the Margrave over the Witch). This can extend to cases where an attack cannot hit me (e.g. Spy effects when I've got enough draw to draw deck regardless) and I hope to sucker my opponent into wasting actions on attacks rather than something better (e.g. Rogue vs Monument) if they end up stopped without enough +action.
Relatedly, I might forgo a simple reveal earlier on (e.g. gain a copper off a single Noble Brigand) in hopes of having my opponent gift me something huge (e.g. they elect to play Kc/Mountebank, I get six silvers).
Other times, it can be more valuable to not reveal information about next hand. E.g. We are near game end and I have Horse Traders it can be worth it for my opponent to be left playing the odds I have Horse traders (and hence can buy two of something to end the game) than getting an extra card and him knowing I can (e.g. he wants to buy an estate for a 1 VP lead, two provinces left, but that will leave just Estates to buy before game ends and he knows I have exactly one Horse traders in my non-engine deck).
Another common-ish thing is when I'm deciding what to top deck for next turn. If I have to set back a terminal with Courtyard, Count, Haven, etc. I'm going to assuredly move back the card your reaction counters and play something else this turn.
There are many, many more cases here, but while these happen all the time, the odds that any of them will decide a game are extremely minute. I could only see this being an issue (and even then a really minor one) in highly competitive play at tournament level.