I think we can all agree that the Champion made some sloppy plays, I know that I've also done some in the past. Sometimes I wonder after a game if I really made a dumb play. It can be hard to remember if you've played a land or not when a turn goes long and Wasteland is involved. Maybe Joseph made other infractions that should have received warnings but if players don't call a judge when they notice an infraction or judges don't issue warnings when they notice one, then accumulated sloppy play won't be punished. So the next time your opponent plays 2 lands, don't pay for a sphere or pays the wrong colour of mana, call a judge and ask him why he doesn't give a warning if you think it's warranted. Even if unintentional, playing or drawing extra cards definitely give an advantage over tournament.
Judges have a PR issue, a lot of people see calling a judge as scummy, mean, etc. It might be because they have the same name as the officer of court giving jail sentences. Maybe players would be less intimidated by referees or rules assistants.
It is my experience that the player's meeting is hugely inefficient and ineffective. Rooms tend to be really and it's difficult, or impossible, to understand what is being especially for non-native English speakers or those not speaking English at all.
I've been more concerned about the missed triggers, especially those concerning Chalice of the Void. It was already known that the missed trigger policy was lacking for triggers affecting objects on the stack. I understand that all the changes that happened in the past were confusing and that some players still don't know how it works. I routinely see players reminding players of beneficial triggers in smaller events. I was really surprised when a player resolved two spells in a row into its own trigger that the players weren't split apart to try to determine if it was done intentionally.
The camera brings players and staff into much more scrutiny than usual. It would be into everyone best interest to have a judge assigned to a camera match just like sports have referees during televised match. It's a bit unfair for players on camera if they get more warnings than other players especially since players can decline to be on camera. It should also be known that judges can't use video replays during a match, except for Pro events, only for investigations later on.