It seems a bit silly to say this, but it’s something that should already exist in Overwatch.
In competitive matches, players shouldn’t be punished for leaving the match, if you restrict the player from being unable to play anything other than returning to the match.
Yes, just like in Paladins, if you press ALT+F4 in the middle of the match or if your game crashes, once you reopen the game immediately after loading the player’s data, it reconnects to the previous match, preventing the player from trying to play another match.
Just recently, the lobby server gave an error and failed to connect to the match, this being a Blizzard problem, instead of canceling and preventing the player from playing, it’s easier to just let the match return…
Especially in competitive, where no one enters to fill that slot.