I'll play it out except when it's KC-Goons-Masquerade.
I never understood why this pin bothered people so much. I've literally never used it or had it used against me in a game of Dominion. Probably because I can't have seen those three cards together more than once or twice in all the thousands of games.
I've seen it one or two times. It doesn't come up often, yeah, but when it does, your entire game becomes: Buy copper, buy curse, pass, every turn. It's entirely not fun. Being beaten by a good engine often gives you some small hope, and you can at least continue scoring points, instead of lose them as your opponent slowly marches towards ending the game.
Yeah, I'm aware of the implications. I just don't particularly care about a degenerate case that occurs once every few thousand games. Why are people bothered by this and not Possession-Forge, which is a two-card pin and therefore far more likely to actually appear?
Wait, how do you pin with Possession-Forge? I don't think I've heard of this and I can't think of how it would work.
It's actually not a two card combo, you need Ambassador or Masquerade and Council Room or Governor (and if you have Council Room and not Governor, you also need a village). And most of the time you also need a Throne effect unless your opponent has a very thin deck. It goes like this (if memory serves me right):
Step 1: Buy a Forge, give it to your opponent with an Ambassador or Masquerade.
Step 2: Buy all the Governors and usually some Throne Rooms or KCs.
Step 3: Every turn, play all of your Governors and make your opponent draw his whole deck, then play Possession. On the possessed turn, play Forge and trash everything. The trashed cards are set aside. Then comes his clean up step, he discards Forge from play, reshuffles the Forge in his discard pile and draws the Forge. Then the set aside cards are returned to his discard pile. He now plays his turn with a Forge and nothing else in his hand.
So it's actually much more complicated than KC/Masq/Goons, and that's also probably why you've never seen it.