If we keep a complete record of all player inputs we can also replay the exact game after the fact, a great feature that arises as a consequence of this design choice.
The observer gets the replay log (cheap), and broadcasts the pixels out (expensive) to the world with very little impact on the game play for the active participants.
Low bandwidth broadcast isn't really relevant I think to esport success -- the "complete" replay aspect to even 1 viewer (the caster) however might be
You both say that the game state is sent to a non-player machine that creates the actual video stream seen by the viewers.
Much more notable is the impact it has on casting, where it's presence is clearly felt -- casters are granted much more freedom, and can be much more thorough and descriptive, when complete replays are available (versus simple dumb video).
We agree about the technogoly -- we disagree on its impact