People in Silicon Valley employ hit men to murder people who give bad references? Do you have any stories of that or links? Seems pretty far fetched
That all said, people usually start with intimidation, and that's usually enough. Very few people believe in their vendettas enough to die for them, and very few people want to kill or have someone killed, just to make a problem go away, if they don't need to do so.
I do have stories, but I'm not going to share them, for obvious reasons. Only one of the ones I know well involved a person actually dying, but quite a few where people were "roughed up" and are now disabled.
Pardon my language, but what the fuck? You honestly have "quite a few" stories about people being physically assaulted because they were bad references?
Silicon Valley is a disgusting place. The less you know, the better for your soul. What-the-fuck is a reasonable reaction.
As for physical consequences of bad references, there's obviously going to be a spectrum. It's very unlikely that someone would get hit for saying something like "I don't like him" at a bar and accidentally costing someone a job. Those things happen, and very few people are irrational or paranoid enough to call in a hit man over something small that isn't going to happen again.
If someone is deliberately running around saying, "You shouldn't hire him" or "He was fired for cause", though, it's inevitable that he's going to get what's coming to him.
Rationally speaking, people usually make this calculation based on what they think the person is going to do in the future. Sometimes the motive is revenge, but usually it's just intimidation. If it's truly a one-off, people usually let it go. If someone is making it impossible to find work, though, then people get desperate.