There's nothing more annoying than getting punished by leaverbuster when I had system issues and league client says "League has crashed". I manage to get it working again, rejoin, win the game, and then after the game punished by leaverbuster for AFK when your client clearly said that it crashed due to a directx error that I then fixed and rejoined the game. Fking retarded.
Regardless if it was intentional or not, your teammates must suffer through a 4v5.
Leavebuster gives you some leeway to account for unintended emergencies. But if those unintended emergencies are frequent enough to trigger the leavebuster, you really need to fix the problem before going into a match-made game.
Test your computer out in some customs first to make sure everything is stable.
Leaverbuster ISN'T about your excuse for afking... it's to protect your teams from having to deal with it.
