Getting out for an early employee after funding rounds is expensive because buying options can hit you with massive tax bills on top of the cost of buying the options. Worse, the stats aren't great for a chance on return. Your lotto ticket gets expensive and risky as soon as you decide to leave.
Articles like this one hammer home more and more to me how little VCs actually value early employees. Paying out founders to stay is a strategic move. Keeping them is worth it because they are the face of the company and turmoil at that level hurts their payout. Burning out early employees is not a concern because you can just swap them without drama. In fact, with the way options are structured and the 'industry wisdom' to hold off purchasing, it feels like a strategic move to burn out early employees since many employees that are forced out often can't even buy their options. They are left with nothing after all that work and risk. From a purely cynical view this is a great thing for VCs since now the company got all the benefit of an early employee and just lost all the costs.
I don't know about the other three points, but I can guarantee you point 1 of 'right sizing perceptions' is wrong.