Sums it up. Most interesting is that more teenagers tend to know what an icon is used for on the computer than what it originally represented. Which makes total sense because they grew up with these icons.
So it might make more sense to ask "to what degree are people used to this icon?" rather than "how many know where this icon came from?".
In this sense, changing established icons (like I would argue the photo app's one) doesn't seem such a good idea.
I'm the organizer of this conference. The stage is very flexible and has many opportunities for trap doors etc. It's honestly just a little creaky.
We've seen other benefits like folks have mentioned. It draws speakers out from behind the podium.
The theater we use is popular and we often didn't have the stage setup until 2AM the night before a 9AM start time. As organizers/hosts we couldn't be up that late.
Sometimes you come in and the stagehands at the venue read the notes about putting down the carpet and they decided to put two carpets instead of one. And the carpets are secured with gaffers tape. And you don't really see an issue with it so you leave it be.
My best guess is an acoustical reason. The floor might reflect the speaker's voice in ways that muddle it for the audience, so those carpets are placed in front of them to kill that reflection?
In the sphere of "talks," I know TED puts a big round carpet on stage that you're supposed to stay on while speaking. More generally for "carpets on stage," I've seen some smaller music venues and studios with carpets to make a nicer area for performers and to absorb unwanted sound (in the case of studios)
Surprising and excellent talk.