You do realise that these warnings would be handed out maybe once or twice in a tournament? And it's not like the TO gets on a megaphone and calls both players out; he'd correct their mistake and tell both players to keep a closer eye on things before moving on. It's likely only the people at the next table over would even notice what had happened. I think that's a fair consequence for allowing your game to go far enough off course to require the TO's intervention in the first place.
As for your statement that no-one would attend events judged like this... well, MTG has this rule, and I don't think they're struggling.