It will help apps which require interaction from users, like google stadia's game streaming. for other use cases, I think one does not care even if the feed is delayed by few seconds.
Another interesting use case someone mentioned here before is the world cup - you don't want a penalty shoot-out ruined by your neighbours cheering a few seconds before you see the goal.
A few seconds would also such for live streaming where the streamer interacts in chat.
A few seconds would also such for live streaming where the streamer interacts in chat.