Exactly, safe to abandon matches should not count in any way or show up in match history. Now could it be that they don't actually count in the background? Maybe, but it still skews your matchmaking history and the stats for the hero you played with in that match.
Just had a match where someone on the enemy team made the unfortunate decision of abandoning the match (Presumably a rage quit). This were then followed with a couple more from the enemy team leaving, meaning we technically had an "easy" win, everyone but myself and two others on the enemy team ended up leaving. So it ended in a loss anyways.
And sure, if it ended in a win I probably wouldn't really have thought much more of it, but seeing it show up as a loss in the match history makes it feels pretty bitter. Even if it ended in a victory, it really shouldn't count in any way, especially if there's more than one person who left the match. It's not a proper match, it skews your overall match history and the given hero's win/loose ratio.