Leavers are a big problem

Why aren't leavers instantly punished? For an example when you DC from most games you're given a like 5 minute timer to reconnect before given an abandon status, and if you do not reconnect in that time you are given a penalty timer where you can't reQ for any competitive/ranked games. 1st time 30mins, 2nd time 2 hours...etc and just continue upwards until like 7 days or until the account is just permabanned by tribunal or something. I would gladly take an occasional punishment for my net DC'ing if it meant that players that are constantly ruining games for others are bullied by the system.