Are you sure? I think business presentations are 99% getting your name out there and 1% teaching people valuable information. I've been to them and I'm not sure how anyone could pay attention to the content because it's very very slow-moving and boring. But now I know the presenter. Hence, it's obvious that this is a social ritual rather than something that makes objective good use of everyone's time. (The audience members attend so that other audience members will remember them too.)
(We recently had some company-wide meeting that was a few hours long. I realized that I could have read an essay version of the "presentation" in five minutes. 1 hour and 55 minutes times 300,000 employees makes presentations a pretty fucking dumb way of sharing information, if the only purpose is in fact to share information.)
Company wide meetings are so that nobody can claim they didn't get the memo. It's not just about sharing information, it's the implicit threat that everyone knows the information has been shared with you. Lots of other ways to solve that problem, but apparently herding everyone in the same room is the accepted default.
(We recently had some company-wide meeting that was a few hours long. I realized that I could have read an essay version of the "presentation" in five minutes. 1 hour and 55 minutes times 300,000 employees makes presentations a pretty fucking dumb way of sharing information, if the only purpose is in fact to share information.)