The problem comes when the situations starts to resemble the line about how, if you owe a bank a billion dollars, you own the bank: if the direction the CEO has taken the company differs enough from the vision of the board, and they've had enough time to develop the company in that direction, they can kinda hold the organization hostage. Yes, the company isn't what the board really wanted it to be, but it's still worth a bajillion dollars: completely unwinding it and starting over is unthinkable, but all the options that include firing the CEO (the only real lever the board has, the foundation of all the decision-making weight that they have, remember) end up looking like that.