Do I have to record stats and results, or can I keep it simple?

You don’t have to record anything. Many organizers use Playbox only to announce games, collect sign-ups and handle payments, and never touch stats.

The lightest way to run a game: create it, let players sign up, play, close the event. That is the whole loop.

If you do record results, entering teams and scores takes about half a minute during the game, and in exchange players get updated ratings, personal stats and a post-game report. That is the usual reason players keep coming back to one particular organizer. A game with no recorded result simply stays unranked: nothing is blocked, commission does not change, and you can start recording whenever you feel like it.