Why do people quit all the time?

Reasons I quit games early.

1. Toxic team mates
2. Useless team mates
3. Only have half hour to play and don't want to spend that time waiting for rez.
4. The first weapon I found was a Mozambique
5. General ragequit

A punishment system is not going to stop me from leaving the game, I'll still quit and go play something else. 

You do know that you can still win the game solo right? I understand that you don't want to be at a disadvantage, but neither do I which is why I quit. You also have the ability to quit, it takes 10 - 20 seconds to find another another match, why punish yourself for 15-20 mins when you know your chances of winning are slim to nil?