This is why I think Blizzard should add some server side code to detect people who keep leaving matches right before they end, after their team losses round 1 of a KotH map or after they lose the first point on a map (just some examples). If you keep leaving during those then you’re clearly leaving before you feel your team might lose. Those that trigger this get a warning that if they continue that they will get a 30min ban.
I play a LOT of Mystery Heroes and you can not play a match without at least 1 person leaving because their team might not win. KotH maps after see 2-3 people bail after losing round 1.