Clearly someone thinks so. They convinced the UK Conservative party to do it a few years back.

https://duckduckgo.com/?q=conservative+power+pose&t=ffab&iax...

I don't think I've seen a single person who doesn't think it looks ridiculous.

Thank you. Now my coffee is on am display. LOL.

It just strikes me as weird. Nobody is going to be impressed by your power stance in some off-brand vans and jeans.

Apple presenters look like typical old-money-rich people to me

Christ they’re obviously coached on more than just their stance. Watch the hand and arm motions. The manner in which those motions are coordinated with the dialog. It’s all one choreographed dance. Those paying close attention will even notice the similarities between speakers. I recall Craig F. doing the same fingers-meet-fingers posture as the MBP lady from todays presentation.

I would wager there is a coach (or several) communicating with each live presenter via an earpiece.

Certainly a lot of full rehearsals.