What is the point of dcing at the last 3 sec of the match, and being treated as a leaver

I’ve been facing this almost 8 times this week and I cannot tolerate this any longer. I’ve been playing the match smoothly throughout the match but at the ending screen (the scene where the core is exploding and the victory/defeat message pop out) I just lagged for 3 secs. Then, the game treated me as a leaver and 1. cancel my 20mins match results 2. mark me as a leaver.
What is the point of playing 20 mins, just dced for 3 sec and ‘punish’ me for dcing? My 160 mins of time play is totally a waste of time! I demand to have what I should recieve in those dced matches and, also, blizz pls improve your leaver system by making unfortunate dced peoples at the very end of the match not counted as a leaver.

ps. this happened in asia network. Hope I am posting in the right place.