Disconnecting from games that you win

Today my friend disconnected from a game due to the league client. We didn't remake because i knew we could win. He came back in 7 minutes later. We won after around 35 minutes. We played a few more, and then i disconnected from 1. I disconnected at about 16 minutes, and reconnected around 22 minutes. We then won after 33 minutes. How is it fair that we both lost LP for these wins? We did the right thing by reconnecting, and helped our team to influence the victory. We were there for the majority of the game. There is currently no incentive to ever reconnect. You are going to lose LP so why bother reconnecting if you are to be punished anyway? I dont care if i dont gain any LP but for me to lose LP for doing the right thing is absolutely a dumb system. Someone please explain why doing the right thing gets you punished?