A crucible is also a container that can withstand extremely high temperatures. It is also the name of a Dalek space station in Doctor Who. There is an episode of Fraiser titled "The Crucible". More accurately, the Crucible you're referring to uses the Salem witch trials as an allegory for the accusations in the United States, at the time of the writing, that some people were communist spies including the author. ...It also sounds cooler than "matchmaking".