Many games can detect when a player disconnects, and give a 1-2 minute timer after which the opposing player can choose to boot the other. Time banks are okay but the fact is, even places with good internet have occasional momentary cut-outs and you need to "earn" your time banks so early game disconnects are devastating, especially in an event with a buy-in. It's just a very frustrating way to lose, and without an enforced grace period, people will just fast-play for the free win if they notice that their opponent seems to have lost connection.