What the Yahoo Board was doing was essentially bringing in their own set of advisers.

But regardless, the board had six members. Altman was actively trying to grow the board (and would presumably add loyal allies), and had previously tried to kick Toner off the board. So just by sheer numbers it's obvious they had to move quietly before they acted. And you saying this is "unprecedented" is just weird - CEOs are fired with little warning all the time, and if they also have board seats, the board members who want to fire them usually figure out if they have enough support before hand.

I think the thing we're probably agreeing on is that the board just handled the communication abysmally. I don't know how they thought they could fire Altman without a detailed explanation, especially to their partners like MS.