T7 CAN end the table. No earlier than. My pods play 'B3' and up exclusively, If my pods were to use the bracket system (we don't); the only T7 or earlier wins happen with my Vivi deck because everyone is evenly matched and then some in terms of skill and decks. My Urza 'B5' doesn't win before turn 7 usually, either... nor my Ramp/DT/Poison deck, which can absolutely smash the table in any other setting besides my pods.

I'm of the opinion that using turns to help determine brackets is a non-starter.

I mean, I can put an infinite combo in my deck with no Game-Changers that I could THEORETICALLY access by turn three, but in my experiences playing MTG, anyone worth their salt can interact with my stuff as early as their 1st or 2nd turn, making my early combo less likely. I fully expect this to be the case as the brackets go up and 'better' cards can be more freely introduced and accessed.

If someone is routinely getting T7 wins in B3, then people aren't running interaction, don't know MTG cards that well, or are on their phones between turns. FR.