Overwatch has known to hand out punishments to people / players who abandon competitive mode. They want to make competitive mode very serious and only for players who want to play seriously. A recent post comment by Jeff Kaplan on Battle.net mentions the same :
We’ll definitely take the idea into consideration. Our philosophy has been that we would rather not have leavers playing the game at all (especially in Competitive Play). We keep increasing the penalty for leaving and will continue to do so. We’re in the process of implementing a new policy which would take into account how many Competitive Seasons you have been banned from and at a certain point, prevent you from playing Competitive ever again.