Hello, I have the same depressing experience. From my today 5 games 4 was stopped due to one or more players leaving when losing. In the 5th game, my teammate began to shoot at me saying that I have slow computer. Sure this may happen, but there should be some way how to deal with such players. I did blow his ass off with my tank, but thats not enough... I mean some perma-ban mechanism, block list accessible quickly ingame or via steam... something. But this way I, and many others will definitely stop playing soon.
I might have some good ideas, how to solve this, if you would like to ask

I mean vietnam and assault squads should solve this issues of Multiplayer, and then we all will be so much content.
Thx 4 reading this.
Michal