I agree that you should always have a pre-recorded version as backup, but live demos communicate a confidence in your product, and that can be worth something. Whenever I see a pre-recorded demo I wonder how many takes it took them, or how many pauses were taken out in editing, etc.
It helps if you have a master of ceremonies capable of running three rings simultaneously. Jobs could do it. Looking at what Apple is doing, they feel Cook is not. You lean into your strengths and avoid your weaknesses. Meta should realize that theZuck is not Jobs and is much closer to Cook
Meta took that risk and failed.