I don't think it is a failure of Cisco that they let Zoom slip out and become a new company. Even if I were a Cisco shareholder I don't know that I'd be that unhappy with management. I can just buy Zoom stock if I think they are on a winner - more than 75% of their market cap came into existence after the IPO.
I don't see who the loser is in this story. It isn't Cisco shareholders; they can be Zoom shareholders too if they want to be.