If the organizer prefers more control, they can assign individuals to bring

It is all about control.
And my point: one does not have to tire oneself over these details. There is no harm if one item is brought twice. So what? Still each one will have it's own unique flavour:)

Thinking and rethinking...

P.S.: How do you manage to assess and gauge the core or crux of my presentation every single time???