This is a really important characteristic of larp vs. tabletop. I wonder if it’s a side-effect of embodiment, rather than a more central part of the definition of larp?
If you have a roleplaying game sitting at a table, where your physical actions are representative of your characters’ (e.g. a boardroom situation), and everyone can hear each other, I would say that’s a larp. But the information flow is more like a tabletop game.
Possibly what distinguishes information flow in a tabletop game is the usual role of the game master, who is like a conduit and arbiter for most information in the game. That’s not usually the case in larp. I think that might be definitional for larp vs. tabletop.
Real time play is another characteristic of larp. The flow of time in the setting is represented by the flow of time in the real world. In tabletop, real time and “game time” are largely divorced, typically only syncing when people are talking in character (in a larp-like manner). In larp it’s the opposite, events usually happen in real time except for exceptions like time freezes and “time bubbles” when abstract combat rules takes a long time to resolve (in a tabletop-like manner).
I think the different ways time flows also spring from the role of the GM as constant facilitator in tabletop. Take away the GM as the intermediary for all actions in the setting, and it frees up the players to play their characters in real time. Especially as freedom from the GM allows players to physically roam and form a distributed network of interaction.
So larp is, in a way, freedom from being managed moment-to-moment by a GM, along with embodiment. These things together have important implications for information flow and time flow that are critical to the practical way a larp functions.